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pkarwasz pushed a commit to branch 
fix/2363_add_logback_throwable_consuming_semantics
in repository https://gitbox.apache.org/repos/asf/logging-log4j2.git

commit fcadb743ec08e1fc2d26482372536b55bc7d2684
Author: Piotr P. Karwasz <[email protected]>
AuthorDate: Thu Mar 14 12:10:52 2024 +0100

    Add Logback's throwable-consuming semantics as an option
    
    The semantics used to determine the `Throwable` attached to a log event
    changed in Logback 1.1.0 (in the fix to 
[LOGBACK-873](https://jira.qos.ch/browse/LOGBACK-873)).
    
    When there are not enough arguments to the log call to fill both the
    throwable field and the placeholders contained in the message pattern,
    Logback 1.1.0 and later prefer to fill the throwable field and leave
    some placeholders empty. Log4j Core does the opposite choice: it first
    fills all the placeholders and only fills the throwable field if there
    is something left.
    
    This change allows `log4j-slf4j-impl` and `log4j-slf4j2-impl` users to
    switch between the two behaviors by setting the property
    `log4j2.messageFactory` to:
    
    ```
    org.apache.logging.slf4j.message.ThrowableConsumingMessageFactory
    ```
---
 .../message/ThrowableConsumingMessageFactory.java  | 187 +++++++++++++++++++++
 .../apache/logging/slf4j/message/package-info.java |  22 +++
 .../ThrowableConsumingMessageFactoryTest.java      | 138 +++++++++++++++
 .../message/ThrowableConsumingMessageFactory.java  | 187 +++++++++++++++++++++
 .../apache/logging/slf4j/message/package-info.java |  22 +++
 .../ThrowableConsumingMessageFactoryTest.java      | 138 +++++++++++++++
 ...3_add_logback_throwable_consuming_semantics.xml |  11 ++
 7 files changed, 705 insertions(+)

diff --git 
a/log4j-slf4j-impl/src/main/java/org/apache/logging/slf4j/message/ThrowableConsumingMessageFactory.java
 
b/log4j-slf4j-impl/src/main/java/org/apache/logging/slf4j/message/ThrowableConsumingMessageFactory.java
new file mode 100644
index 0000000000..cb55499c71
--- /dev/null
+++ 
b/log4j-slf4j-impl/src/main/java/org/apache/logging/slf4j/message/ThrowableConsumingMessageFactory.java
@@ -0,0 +1,187 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to you under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.logging.slf4j.message;
+
+import java.util.Arrays;
+import org.apache.logging.log4j.message.Message;
+import org.apache.logging.log4j.message.MessageFactory2;
+import org.apache.logging.log4j.message.ObjectMessage;
+import org.apache.logging.log4j.message.ParameterizedMessage;
+import org.apache.logging.log4j.message.SimpleMessage;
+
+/**
+ * A message factory that eagerly removes a trailing throwable argument.
+ * <p>
+ *     This factory implements the algorithm used by Logback 1.1.x or later to 
determine
+ *     {@link Message#getThrowable()}: if the last argument is a {@link 
Throwable} and there are less arguments than
+ *     the number of placeholders incremented by one, the last argument will 
be used as
+ *     {@link Message#getThrowable()} and will <strong>not</strong> appear in 
the parameterized message.
+ * </p>
+ * <p>
+ *     The usual Log4j semantic only looks for throwables once 
<strong>all</strong> the placeholders have been filled.
+ * </p>
+ * @since 2.24.0
+ */
+public final class ThrowableConsumingMessageFactory implements MessageFactory2 
{
+
+    private Message newParameterizedMessage(final Object throwable, final 
String pattern, final Object... args) {
+        return new ParameterizedMessage(pattern, args, (Throwable) throwable);
+    }
+
+    @Override
+    public Message newMessage(final Object message) {
+        return new ObjectMessage(message);
+    }
+
+    @Override
+    public Message newMessage(final String message) {
+        return new SimpleMessage(message);
+    }
+
+    @Override
+    public Message newMessage(final String message, final Object... params) {
+        if (params != null && params.length > 0) {
+            final Object lastArg = params[params.length - 1];
+            return lastArg instanceof Throwable
+                    ? newParameterizedMessage(lastArg, message, 
Arrays.copyOf(params, params.length - 1))
+                    : newParameterizedMessage(null, message, params);
+        }
+        return new SimpleMessage(message);
+    }
+
+    @Override
+    public Message newMessage(final CharSequence charSequence) {
+        return new SimpleMessage(charSequence);
+    }
+
+    @Override
+    public Message newMessage(final String message, final Object p0) {
+        return p0 instanceof Throwable
+                ? newParameterizedMessage(p0, message)
+                : newParameterizedMessage(null, message, p0);
+    }
+
+    @Override
+    public Message newMessage(final String message, final Object p0, final 
Object p1) {
+        return p1 instanceof Throwable
+                ? newParameterizedMessage(p1, message, p0)
+                : newParameterizedMessage(null, message, p0, p1);
+    }
+
+    @Override
+    public Message newMessage(final String message, final Object p0, final 
Object p1, final Object p2) {
+        return p2 instanceof Throwable
+                ? newParameterizedMessage(p2, message, p0, p1)
+                : newParameterizedMessage(null, message, p0, p1, p2);
+    }
+
+    @Override
+    public Message newMessage(
+            final String message, final Object p0, final Object p1, final 
Object p2, final Object p3) {
+        return p3 instanceof Throwable
+                ? newParameterizedMessage(p3, message, p0, p1, p2)
+                : newParameterizedMessage(null, message, p0, p1, p2, p3);
+    }
+
+    @Override
+    public Message newMessage(
+            final String message, final Object p0, final Object p1, final 
Object p2, final Object p3, final Object p4) {
+        return p4 instanceof Throwable
+                ? newParameterizedMessage(p4, message, p0, p1, p2, p3)
+                : newParameterizedMessage(null, message, p0, p1, p2, p3, p4);
+    }
+
+    @Override
+    public Message newMessage(
+            final String message,
+            final Object p0,
+            final Object p1,
+            final Object p2,
+            final Object p3,
+            final Object p4,
+            final Object p5) {
+        return p5 instanceof Throwable
+                ? newParameterizedMessage(p5, message, p0, p1, p2, p3, p4)
+                : newParameterizedMessage(null, message, p0, p1, p2, p3, p4, 
p5);
+    }
+
+    @Override
+    public Message newMessage(
+            final String message,
+            final Object p0,
+            final Object p1,
+            final Object p2,
+            final Object p3,
+            final Object p4,
+            final Object p5,
+            final Object p6) {
+        return p6 instanceof Throwable
+                ? newParameterizedMessage(p6, message, p0, p1, p2, p3, p4, p5)
+                : newParameterizedMessage(null, message, p0, p1, p2, p3, p4, 
p5, p6);
+    }
+
+    @Override
+    public Message newMessage(
+            final String message,
+            final Object p0,
+            final Object p1,
+            final Object p2,
+            final Object p3,
+            final Object p4,
+            final Object p5,
+            final Object p6,
+            final Object p7) {
+        return p7 instanceof Throwable
+                ? newParameterizedMessage(p7, message, p0, p1, p2, p3, p4, p5, 
p6)
+                : newParameterizedMessage(null, message, p0, p1, p2, p3, p4, 
p5, p6, p7);
+    }
+
+    @Override
+    public Message newMessage(
+            final String message,
+            final Object p0,
+            final Object p1,
+            final Object p2,
+            final Object p3,
+            final Object p4,
+            final Object p5,
+            final Object p6,
+            final Object p7,
+            final Object p8) {
+        return p8 instanceof Throwable
+                ? newParameterizedMessage(p8, message, p0, p1, p2, p3, p4, p5, 
p6, p7)
+                : newParameterizedMessage(null, message, p0, p1, p2, p3, p4, 
p5, p6, p7, p8);
+    }
+
+    @Override
+    public Message newMessage(
+            final String message,
+            final Object p0,
+            final Object p1,
+            final Object p2,
+            final Object p3,
+            final Object p4,
+            final Object p5,
+            final Object p6,
+            final Object p7,
+            final Object p8,
+            final Object p9) {
+        return p9 instanceof Throwable
+                ? newParameterizedMessage(p9, message, p0, p1, p2, p3, p4, p5, 
p6, p7, p8)
+                : newParameterizedMessage(null, message, p0, p1, p2, p3, p4, 
p5, p6, p7, p8, p9);
+    }
+}
diff --git 
a/log4j-slf4j-impl/src/main/java/org/apache/logging/slf4j/message/package-info.java
 
b/log4j-slf4j-impl/src/main/java/org/apache/logging/slf4j/message/package-info.java
new file mode 100644
index 0000000000..764c1cf518
--- /dev/null
+++ 
b/log4j-slf4j-impl/src/main/java/org/apache/logging/slf4j/message/package-info.java
@@ -0,0 +1,22 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache license, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the license for the specific language governing permissions and
+ * limitations under the license.
+ */
+@Export
+@Version("2.24.0")
+package org.apache.logging.slf4j.message;
+
+import org.osgi.annotation.bundle.Export;
+import org.osgi.annotation.versioning.Version;
diff --git 
a/log4j-slf4j-impl/src/test/java/org/apache/logging/slf4j/message/ThrowableConsumingMessageFactoryTest.java
 
b/log4j-slf4j-impl/src/test/java/org/apache/logging/slf4j/message/ThrowableConsumingMessageFactoryTest.java
new file mode 100644
index 0000000000..2a111be434
--- /dev/null
+++ 
b/log4j-slf4j-impl/src/test/java/org/apache/logging/slf4j/message/ThrowableConsumingMessageFactoryTest.java
@@ -0,0 +1,138 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to you under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.logging.slf4j.message;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import org.apache.logging.log4j.message.Message;
+import org.apache.logging.log4j.message.MessageFactory2;
+import org.junit.jupiter.api.Test;
+
+public class ThrowableConsumingMessageFactoryTest {
+
+    private static final String MESSAGE = "MESSAGE";
+    private static final Object P0 = new Object();
+    private static final Object P1 = new Object();
+    private static final Object P2 = new Object();
+    private static final Object P3 = new Object();
+    private static final Object P4 = new Object();
+    private static final Object P5 = new Object();
+    private static final Object P6 = new Object();
+    private static final Object P7 = new Object();
+    private static final Object P8 = new Object();
+    private static final Object P9 = new Object();
+    private static final Object P10 = new Object();
+    private static final Object THROWABLE = new Throwable();
+
+    @Test
+    void should_not_consume_last_object_parameter() {
+        final MessageFactory2 factory = new ThrowableConsumingMessageFactory();
+        assertThat(factory.newMessage(MESSAGE, P0))
+                .extracting(m -> m.getParameters().length, 
Message::getThrowable)
+                .as("checking parameter count and throwable")
+                .containsExactly(1, null);
+        assertThat(factory.newMessage(MESSAGE, P0, P1))
+                .extracting(m -> m.getParameters().length, 
Message::getThrowable)
+                .as("checking parameter count and throwable")
+                .containsExactly(2, null);
+        assertThat(factory.newMessage(MESSAGE, P0, P1, P2))
+                .extracting(m -> m.getParameters().length, 
Message::getThrowable)
+                .as("checking parameter count and throwable")
+                .containsExactly(3, null);
+        assertThat(factory.newMessage(MESSAGE, P0, P1, P2, P3))
+                .extracting(m -> m.getParameters().length, 
Message::getThrowable)
+                .as("checking parameter count and throwable")
+                .containsExactly(4, null);
+        assertThat(factory.newMessage(MESSAGE, P0, P1, P2, P3, P4))
+                .extracting(m -> m.getParameters().length, 
Message::getThrowable)
+                .as("checking parameter count and throwable")
+                .containsExactly(5, null);
+        assertThat(factory.newMessage(MESSAGE, P0, P1, P2, P3, P4, P5))
+                .extracting(m -> m.getParameters().length, 
Message::getThrowable)
+                .as("checking parameter count and throwable")
+                .containsExactly(6, null);
+        assertThat(factory.newMessage(MESSAGE, P0, P1, P2, P3, P4, P5, P6))
+                .extracting(m -> m.getParameters().length, 
Message::getThrowable)
+                .as("checking parameter count and throwable")
+                .containsExactly(7, null);
+        assertThat(factory.newMessage(MESSAGE, P0, P1, P2, P3, P4, P5, P6, P7))
+                .extracting(m -> m.getParameters().length, 
Message::getThrowable)
+                .as("checking parameter count and throwable")
+                .containsExactly(8, null);
+        assertThat(factory.newMessage(MESSAGE, P0, P1, P2, P3, P4, P5, P6, P7, 
P8))
+                .extracting(m -> m.getParameters().length, 
Message::getThrowable)
+                .as("checking parameter count and throwable")
+                .containsExactly(9, null);
+        assertThat(factory.newMessage(MESSAGE, P0, P1, P2, P3, P4, P5, P6, P7, 
P8, P9))
+                .extracting(m -> m.getParameters().length, 
Message::getThrowable)
+                .as("checking parameter count and throwable")
+                .containsExactly(10, null);
+        assertThat(factory.newMessage(MESSAGE, P0, P1, P2, P3, P4, P5, P6, P7, 
P8, P9, P10))
+                .extracting(m -> m.getParameters().length, 
Message::getThrowable)
+                .as("checking parameter count and throwable")
+                .containsExactly(11, null);
+    }
+
+    @Test
+    void should_consume_last_throwable_parameter() {
+        final MessageFactory2 factory = new ThrowableConsumingMessageFactory();
+        assertThat(factory.newMessage(MESSAGE, THROWABLE))
+                .extracting(m -> m.getParameters().length, 
Message::getThrowable)
+                .as("checking parameter count and throwable")
+                .containsExactly(0, THROWABLE);
+        assertThat(factory.newMessage(MESSAGE, P0, THROWABLE))
+                .extracting(m -> m.getParameters().length, 
Message::getThrowable)
+                .as("checking parameter count and throwable")
+                .containsExactly(1, THROWABLE);
+        assertThat(factory.newMessage(MESSAGE, P0, P1, THROWABLE))
+                .extracting(m -> m.getParameters().length, 
Message::getThrowable)
+                .as("checking parameter count and throwable")
+                .containsExactly(2, THROWABLE);
+        assertThat(factory.newMessage(MESSAGE, P0, P1, P2, THROWABLE))
+                .extracting(m -> m.getParameters().length, 
Message::getThrowable)
+                .as("checking parameter count and throwable")
+                .containsExactly(3, THROWABLE);
+        assertThat(factory.newMessage(MESSAGE, P0, P1, P2, P3, THROWABLE))
+                .extracting(m -> m.getParameters().length, 
Message::getThrowable)
+                .as("checking parameter count and throwable")
+                .containsExactly(4, THROWABLE);
+        assertThat(factory.newMessage(MESSAGE, P0, P1, P2, P3, P4, THROWABLE))
+                .extracting(m -> m.getParameters().length, 
Message::getThrowable)
+                .as("checking parameter count and throwable")
+                .containsExactly(5, THROWABLE);
+        assertThat(factory.newMessage(MESSAGE, P0, P1, P2, P3, P4, P5, 
THROWABLE))
+                .extracting(m -> m.getParameters().length, 
Message::getThrowable)
+                .as("checking parameter count and throwable")
+                .containsExactly(6, THROWABLE);
+        assertThat(factory.newMessage(MESSAGE, P0, P1, P2, P3, P4, P5, P6, 
THROWABLE))
+                .extracting(m -> m.getParameters().length, 
Message::getThrowable)
+                .as("checking parameter count and throwable")
+                .containsExactly(7, THROWABLE);
+        assertThat(factory.newMessage(MESSAGE, P0, P1, P2, P3, P4, P5, P6, P7, 
THROWABLE))
+                .extracting(m -> m.getParameters().length, 
Message::getThrowable)
+                .as("checking parameter count and throwable")
+                .containsExactly(8, THROWABLE);
+        assertThat(factory.newMessage(MESSAGE, P0, P1, P2, P3, P4, P5, P6, P7, 
P8, THROWABLE))
+                .extracting(m -> m.getParameters().length, 
Message::getThrowable)
+                .as("checking parameter count and throwable")
+                .containsExactly(9, THROWABLE);
+        assertThat(factory.newMessage(MESSAGE, P0, P1, P2, P3, P4, P5, P6, P7, 
P8, P9, THROWABLE))
+                .extracting(m -> m.getParameters().length, 
Message::getThrowable)
+                .as("checking parameter count and throwable")
+                .containsExactly(10, THROWABLE);
+    }
+}
diff --git 
a/log4j-slf4j2-impl/src/main/java/org/apache/logging/slf4j/message/ThrowableConsumingMessageFactory.java
 
b/log4j-slf4j2-impl/src/main/java/org/apache/logging/slf4j/message/ThrowableConsumingMessageFactory.java
new file mode 100644
index 0000000000..cb55499c71
--- /dev/null
+++ 
b/log4j-slf4j2-impl/src/main/java/org/apache/logging/slf4j/message/ThrowableConsumingMessageFactory.java
@@ -0,0 +1,187 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to you under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.logging.slf4j.message;
+
+import java.util.Arrays;
+import org.apache.logging.log4j.message.Message;
+import org.apache.logging.log4j.message.MessageFactory2;
+import org.apache.logging.log4j.message.ObjectMessage;
+import org.apache.logging.log4j.message.ParameterizedMessage;
+import org.apache.logging.log4j.message.SimpleMessage;
+
+/**
+ * A message factory that eagerly removes a trailing throwable argument.
+ * <p>
+ *     This factory implements the algorithm used by Logback 1.1.x or later to 
determine
+ *     {@link Message#getThrowable()}: if the last argument is a {@link 
Throwable} and there are less arguments than
+ *     the number of placeholders incremented by one, the last argument will 
be used as
+ *     {@link Message#getThrowable()} and will <strong>not</strong> appear in 
the parameterized message.
+ * </p>
+ * <p>
+ *     The usual Log4j semantic only looks for throwables once 
<strong>all</strong> the placeholders have been filled.
+ * </p>
+ * @since 2.24.0
+ */
+public final class ThrowableConsumingMessageFactory implements MessageFactory2 
{
+
+    private Message newParameterizedMessage(final Object throwable, final 
String pattern, final Object... args) {
+        return new ParameterizedMessage(pattern, args, (Throwable) throwable);
+    }
+
+    @Override
+    public Message newMessage(final Object message) {
+        return new ObjectMessage(message);
+    }
+
+    @Override
+    public Message newMessage(final String message) {
+        return new SimpleMessage(message);
+    }
+
+    @Override
+    public Message newMessage(final String message, final Object... params) {
+        if (params != null && params.length > 0) {
+            final Object lastArg = params[params.length - 1];
+            return lastArg instanceof Throwable
+                    ? newParameterizedMessage(lastArg, message, 
Arrays.copyOf(params, params.length - 1))
+                    : newParameterizedMessage(null, message, params);
+        }
+        return new SimpleMessage(message);
+    }
+
+    @Override
+    public Message newMessage(final CharSequence charSequence) {
+        return new SimpleMessage(charSequence);
+    }
+
+    @Override
+    public Message newMessage(final String message, final Object p0) {
+        return p0 instanceof Throwable
+                ? newParameterizedMessage(p0, message)
+                : newParameterizedMessage(null, message, p0);
+    }
+
+    @Override
+    public Message newMessage(final String message, final Object p0, final 
Object p1) {
+        return p1 instanceof Throwable
+                ? newParameterizedMessage(p1, message, p0)
+                : newParameterizedMessage(null, message, p0, p1);
+    }
+
+    @Override
+    public Message newMessage(final String message, final Object p0, final 
Object p1, final Object p2) {
+        return p2 instanceof Throwable
+                ? newParameterizedMessage(p2, message, p0, p1)
+                : newParameterizedMessage(null, message, p0, p1, p2);
+    }
+
+    @Override
+    public Message newMessage(
+            final String message, final Object p0, final Object p1, final 
Object p2, final Object p3) {
+        return p3 instanceof Throwable
+                ? newParameterizedMessage(p3, message, p0, p1, p2)
+                : newParameterizedMessage(null, message, p0, p1, p2, p3);
+    }
+
+    @Override
+    public Message newMessage(
+            final String message, final Object p0, final Object p1, final 
Object p2, final Object p3, final Object p4) {
+        return p4 instanceof Throwable
+                ? newParameterizedMessage(p4, message, p0, p1, p2, p3)
+                : newParameterizedMessage(null, message, p0, p1, p2, p3, p4);
+    }
+
+    @Override
+    public Message newMessage(
+            final String message,
+            final Object p0,
+            final Object p1,
+            final Object p2,
+            final Object p3,
+            final Object p4,
+            final Object p5) {
+        return p5 instanceof Throwable
+                ? newParameterizedMessage(p5, message, p0, p1, p2, p3, p4)
+                : newParameterizedMessage(null, message, p0, p1, p2, p3, p4, 
p5);
+    }
+
+    @Override
+    public Message newMessage(
+            final String message,
+            final Object p0,
+            final Object p1,
+            final Object p2,
+            final Object p3,
+            final Object p4,
+            final Object p5,
+            final Object p6) {
+        return p6 instanceof Throwable
+                ? newParameterizedMessage(p6, message, p0, p1, p2, p3, p4, p5)
+                : newParameterizedMessage(null, message, p0, p1, p2, p3, p4, 
p5, p6);
+    }
+
+    @Override
+    public Message newMessage(
+            final String message,
+            final Object p0,
+            final Object p1,
+            final Object p2,
+            final Object p3,
+            final Object p4,
+            final Object p5,
+            final Object p6,
+            final Object p7) {
+        return p7 instanceof Throwable
+                ? newParameterizedMessage(p7, message, p0, p1, p2, p3, p4, p5, 
p6)
+                : newParameterizedMessage(null, message, p0, p1, p2, p3, p4, 
p5, p6, p7);
+    }
+
+    @Override
+    public Message newMessage(
+            final String message,
+            final Object p0,
+            final Object p1,
+            final Object p2,
+            final Object p3,
+            final Object p4,
+            final Object p5,
+            final Object p6,
+            final Object p7,
+            final Object p8) {
+        return p8 instanceof Throwable
+                ? newParameterizedMessage(p8, message, p0, p1, p2, p3, p4, p5, 
p6, p7)
+                : newParameterizedMessage(null, message, p0, p1, p2, p3, p4, 
p5, p6, p7, p8);
+    }
+
+    @Override
+    public Message newMessage(
+            final String message,
+            final Object p0,
+            final Object p1,
+            final Object p2,
+            final Object p3,
+            final Object p4,
+            final Object p5,
+            final Object p6,
+            final Object p7,
+            final Object p8,
+            final Object p9) {
+        return p9 instanceof Throwable
+                ? newParameterizedMessage(p9, message, p0, p1, p2, p3, p4, p5, 
p6, p7, p8)
+                : newParameterizedMessage(null, message, p0, p1, p2, p3, p4, 
p5, p6, p7, p8, p9);
+    }
+}
diff --git 
a/log4j-slf4j2-impl/src/main/java/org/apache/logging/slf4j/message/package-info.java
 
b/log4j-slf4j2-impl/src/main/java/org/apache/logging/slf4j/message/package-info.java
new file mode 100644
index 0000000000..764c1cf518
--- /dev/null
+++ 
b/log4j-slf4j2-impl/src/main/java/org/apache/logging/slf4j/message/package-info.java
@@ -0,0 +1,22 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache license, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the license for the specific language governing permissions and
+ * limitations under the license.
+ */
+@Export
+@Version("2.24.0")
+package org.apache.logging.slf4j.message;
+
+import org.osgi.annotation.bundle.Export;
+import org.osgi.annotation.versioning.Version;
diff --git 
a/log4j-slf4j2-impl/src/test/java/org/apache/logging/slf4j/message/ThrowableConsumingMessageFactoryTest.java
 
b/log4j-slf4j2-impl/src/test/java/org/apache/logging/slf4j/message/ThrowableConsumingMessageFactoryTest.java
new file mode 100644
index 0000000000..2a111be434
--- /dev/null
+++ 
b/log4j-slf4j2-impl/src/test/java/org/apache/logging/slf4j/message/ThrowableConsumingMessageFactoryTest.java
@@ -0,0 +1,138 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to you under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.logging.slf4j.message;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import org.apache.logging.log4j.message.Message;
+import org.apache.logging.log4j.message.MessageFactory2;
+import org.junit.jupiter.api.Test;
+
+public class ThrowableConsumingMessageFactoryTest {
+
+    private static final String MESSAGE = "MESSAGE";
+    private static final Object P0 = new Object();
+    private static final Object P1 = new Object();
+    private static final Object P2 = new Object();
+    private static final Object P3 = new Object();
+    private static final Object P4 = new Object();
+    private static final Object P5 = new Object();
+    private static final Object P6 = new Object();
+    private static final Object P7 = new Object();
+    private static final Object P8 = new Object();
+    private static final Object P9 = new Object();
+    private static final Object P10 = new Object();
+    private static final Object THROWABLE = new Throwable();
+
+    @Test
+    void should_not_consume_last_object_parameter() {
+        final MessageFactory2 factory = new ThrowableConsumingMessageFactory();
+        assertThat(factory.newMessage(MESSAGE, P0))
+                .extracting(m -> m.getParameters().length, 
Message::getThrowable)
+                .as("checking parameter count and throwable")
+                .containsExactly(1, null);
+        assertThat(factory.newMessage(MESSAGE, P0, P1))
+                .extracting(m -> m.getParameters().length, 
Message::getThrowable)
+                .as("checking parameter count and throwable")
+                .containsExactly(2, null);
+        assertThat(factory.newMessage(MESSAGE, P0, P1, P2))
+                .extracting(m -> m.getParameters().length, 
Message::getThrowable)
+                .as("checking parameter count and throwable")
+                .containsExactly(3, null);
+        assertThat(factory.newMessage(MESSAGE, P0, P1, P2, P3))
+                .extracting(m -> m.getParameters().length, 
Message::getThrowable)
+                .as("checking parameter count and throwable")
+                .containsExactly(4, null);
+        assertThat(factory.newMessage(MESSAGE, P0, P1, P2, P3, P4))
+                .extracting(m -> m.getParameters().length, 
Message::getThrowable)
+                .as("checking parameter count and throwable")
+                .containsExactly(5, null);
+        assertThat(factory.newMessage(MESSAGE, P0, P1, P2, P3, P4, P5))
+                .extracting(m -> m.getParameters().length, 
Message::getThrowable)
+                .as("checking parameter count and throwable")
+                .containsExactly(6, null);
+        assertThat(factory.newMessage(MESSAGE, P0, P1, P2, P3, P4, P5, P6))
+                .extracting(m -> m.getParameters().length, 
Message::getThrowable)
+                .as("checking parameter count and throwable")
+                .containsExactly(7, null);
+        assertThat(factory.newMessage(MESSAGE, P0, P1, P2, P3, P4, P5, P6, P7))
+                .extracting(m -> m.getParameters().length, 
Message::getThrowable)
+                .as("checking parameter count and throwable")
+                .containsExactly(8, null);
+        assertThat(factory.newMessage(MESSAGE, P0, P1, P2, P3, P4, P5, P6, P7, 
P8))
+                .extracting(m -> m.getParameters().length, 
Message::getThrowable)
+                .as("checking parameter count and throwable")
+                .containsExactly(9, null);
+        assertThat(factory.newMessage(MESSAGE, P0, P1, P2, P3, P4, P5, P6, P7, 
P8, P9))
+                .extracting(m -> m.getParameters().length, 
Message::getThrowable)
+                .as("checking parameter count and throwable")
+                .containsExactly(10, null);
+        assertThat(factory.newMessage(MESSAGE, P0, P1, P2, P3, P4, P5, P6, P7, 
P8, P9, P10))
+                .extracting(m -> m.getParameters().length, 
Message::getThrowable)
+                .as("checking parameter count and throwable")
+                .containsExactly(11, null);
+    }
+
+    @Test
+    void should_consume_last_throwable_parameter() {
+        final MessageFactory2 factory = new ThrowableConsumingMessageFactory();
+        assertThat(factory.newMessage(MESSAGE, THROWABLE))
+                .extracting(m -> m.getParameters().length, 
Message::getThrowable)
+                .as("checking parameter count and throwable")
+                .containsExactly(0, THROWABLE);
+        assertThat(factory.newMessage(MESSAGE, P0, THROWABLE))
+                .extracting(m -> m.getParameters().length, 
Message::getThrowable)
+                .as("checking parameter count and throwable")
+                .containsExactly(1, THROWABLE);
+        assertThat(factory.newMessage(MESSAGE, P0, P1, THROWABLE))
+                .extracting(m -> m.getParameters().length, 
Message::getThrowable)
+                .as("checking parameter count and throwable")
+                .containsExactly(2, THROWABLE);
+        assertThat(factory.newMessage(MESSAGE, P0, P1, P2, THROWABLE))
+                .extracting(m -> m.getParameters().length, 
Message::getThrowable)
+                .as("checking parameter count and throwable")
+                .containsExactly(3, THROWABLE);
+        assertThat(factory.newMessage(MESSAGE, P0, P1, P2, P3, THROWABLE))
+                .extracting(m -> m.getParameters().length, 
Message::getThrowable)
+                .as("checking parameter count and throwable")
+                .containsExactly(4, THROWABLE);
+        assertThat(factory.newMessage(MESSAGE, P0, P1, P2, P3, P4, THROWABLE))
+                .extracting(m -> m.getParameters().length, 
Message::getThrowable)
+                .as("checking parameter count and throwable")
+                .containsExactly(5, THROWABLE);
+        assertThat(factory.newMessage(MESSAGE, P0, P1, P2, P3, P4, P5, 
THROWABLE))
+                .extracting(m -> m.getParameters().length, 
Message::getThrowable)
+                .as("checking parameter count and throwable")
+                .containsExactly(6, THROWABLE);
+        assertThat(factory.newMessage(MESSAGE, P0, P1, P2, P3, P4, P5, P6, 
THROWABLE))
+                .extracting(m -> m.getParameters().length, 
Message::getThrowable)
+                .as("checking parameter count and throwable")
+                .containsExactly(7, THROWABLE);
+        assertThat(factory.newMessage(MESSAGE, P0, P1, P2, P3, P4, P5, P6, P7, 
THROWABLE))
+                .extracting(m -> m.getParameters().length, 
Message::getThrowable)
+                .as("checking parameter count and throwable")
+                .containsExactly(8, THROWABLE);
+        assertThat(factory.newMessage(MESSAGE, P0, P1, P2, P3, P4, P5, P6, P7, 
P8, THROWABLE))
+                .extracting(m -> m.getParameters().length, 
Message::getThrowable)
+                .as("checking parameter count and throwable")
+                .containsExactly(9, THROWABLE);
+        assertThat(factory.newMessage(MESSAGE, P0, P1, P2, P3, P4, P5, P6, P7, 
P8, P9, THROWABLE))
+                .extracting(m -> m.getParameters().length, 
Message::getThrowable)
+                .as("checking parameter count and throwable")
+                .containsExactly(10, THROWABLE);
+    }
+}
diff --git 
a/src/changelog/.2.x.x/2363_add_logback_throwable_consuming_semantics.xml 
b/src/changelog/.2.x.x/2363_add_logback_throwable_consuming_semantics.xml
new file mode 100644
index 0000000000..10326eb1dd
--- /dev/null
+++ b/src/changelog/.2.x.x/2363_add_logback_throwable_consuming_semantics.xml
@@ -0,0 +1,11 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<entry xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance";
+       xmlns="http://logging.apache.org/log4j/changelog";
+       xsi:schemaLocation="http://logging.apache.org/log4j/changelog 
https://logging.apache.org/log4j/changelog-0.1.3.xsd";
+       type="added">
+  <issue id="2363" link="https://github.com/apache/logging-log4j2/pull/2363"/>
+  <description format="asciidoc">
+    Add Logback throwable-consuming semantics as an option in 
`log4j-slf4j-impl` and `log4j-slf4j2-impl`.
+    Users can enable it by setting the property `log4j2.messageFactory` to 
`org.apache.logging.slf4j.message.ThrowableConsumingMessageFactory`.
+  </description>
+</entry>


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