gemini-code-assist[bot] commented on code in PR #38264: URL: https://github.com/apache/beam/pull/38264#discussion_r3149662316
########## sdks/java/io/google-cloud-platform/src/main/java/org/apache/beam/sdk/io/gcp/bigquery/AppendClientCache.java: ########## @@ -0,0 +1,140 @@ +/* + * 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.beam.sdk.io.gcp.bigquery; + +import java.util.concurrent.Callable; +import java.util.concurrent.ExecutorService; +import java.util.concurrent.Executors; +import java.util.concurrent.TimeUnit; +import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.cache.Cache; +import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.cache.CacheBuilder; +import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.cache.RemovalNotification; +import org.checkerframework.checker.nullness.qual.NonNull; +import org.checkerframework.checker.nullness.qual.Nullable; +import org.joda.time.Duration; +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +/** + * Encapsulates the cache of {@link AppendClientInfo} objects and the synchronization protocol + * required to use them safely. The Guava cache object is thread-safe. However our protocol requires + * that client pin the StreamAppendClient after looking up the cache, and we must ensure that the + * cache is not accessed in between the lookup and the pin (any access of the cache could trigger + * element expiration). + */ +class AppendClientCache<KeyT extends @NonNull Object> { + private static final Logger LOG = LoggerFactory.getLogger(AppendClientCache.class); + private final ExecutorService closeWriterExecutor = Executors.newCachedThreadPool(); Review Comment:  It is recommended to use a named `ThreadFactory` with daemon threads for the `ExecutorService`. This improves observability in thread dumps and ensures that the threads do not prevent the JVM from exiting if the process is shutting down. ```java private final ExecutorService closeWriterExecutor = Executors.newCachedThreadPool( new org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.util.concurrent.ThreadFactoryBuilder() .setDaemon(true) .setNameFormat("AppendClientCache-closer-%d") .build()); ``` ########## sdks/java/io/google-cloud-platform/src/main/java/org/apache/beam/sdk/io/gcp/bigquery/AppendClientInfo.java: ########## @@ -134,7 +143,18 @@ public AppendClientInfo withAppendClient( public void close() { BigQueryServices.StreamAppendClient client = getStreamAppendClient(); if (client != null) { - getCloseAppendClient().accept(client); + try { + getCloseAppendClient().accept(client); + } catch (Exception e) { + // We ignore errors when closing clients. + String msg = + e + + "\n" + + Arrays.stream(e.getStackTrace()) + .map(StackTraceElement::toString) + .collect(Collectors.joining("\n")); + LOG.warn("Caught exception whilw trying to close append client. Ignoring {}", msg); Review Comment:  The manual formatting of the stack trace is redundant and inefficient. SLF4J's logger can handle exceptions directly, which includes printing the stack trace. Additionally, there is a typo in the log message ('whilw' instead of 'while'). ```java LOG.warn("Caught exception while trying to close append client. Ignoring", e); ``` ########## sdks/java/io/google-cloud-platform/src/main/java/org/apache/beam/sdk/io/gcp/bigquery/AppendClientCache.java: ########## @@ -0,0 +1,140 @@ +/* + * 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.beam.sdk.io.gcp.bigquery; + +import java.util.concurrent.Callable; +import java.util.concurrent.ExecutorService; +import java.util.concurrent.Executors; +import java.util.concurrent.TimeUnit; +import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.cache.Cache; +import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.cache.CacheBuilder; +import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.cache.RemovalNotification; +import org.checkerframework.checker.nullness.qual.NonNull; +import org.checkerframework.checker.nullness.qual.Nullable; +import org.joda.time.Duration; +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +/** + * Encapsulates the cache of {@link AppendClientInfo} objects and the synchronization protocol + * required to use them safely. The Guava cache object is thread-safe. However our protocol requires + * that client pin the StreamAppendClient after looking up the cache, and we must ensure that the + * cache is not accessed in between the lookup and the pin (any access of the cache could trigger + * element expiration). + */ +class AppendClientCache<KeyT extends @NonNull Object> { + private static final Logger LOG = LoggerFactory.getLogger(AppendClientCache.class); + private final ExecutorService closeWriterExecutor = Executors.newCachedThreadPool(); + + private final Cache<KeyT, AppendClientInfo> appendCache; + + @SuppressWarnings({"FutureReturnValueIgnored"}) + AppendClientCache(Duration expireAfterAccess) { + this.appendCache = + CacheBuilder.newBuilder() + .expireAfterAccess(expireAfterAccess.getMillis(), TimeUnit.MILLISECONDS) + .removalListener( + (RemovalNotification<KeyT, AppendClientInfo> removal) -> { + LOG.info("Expiring append client for {}", removal.getKey()); + final @Nullable AppendClientInfo appendClientInfo = removal.getValue(); + if (appendClientInfo != null) { + // Remove the pin owned by the cache itself. Since the client has not been + // marked as closed, we + // can call unpin in this thread without worrying about blocking the thread. + appendClientInfo.unpinAppendClient(null); + // Close the client in another thread to avoid blocking the main thread. + closeWriterExecutor.submit(appendClientInfo::close); + } + }) + .build(); + } + + // The cache itself always own one pin on the object. This Callable is always used to ensure that + // the cache + // adds a pin before loading a value. + private static Callable<AppendClientInfo> wrapWithPin(Callable<AppendClientInfo> loader) { + return () -> { + AppendClientInfo client = loader.call(); + client.pinAppendClient(); + return client; + }; + } + + /** + * Atomically get an append client from the cache and add a pin. This pin is owned by the client, + * which has the responsibility of removing it. If the client is not in the cache, loader will be + * used to load the client; in this case an additional pin will be added owned by the cache, + * removed when the item is evicted. + */ + public AppendClientInfo getAndPin(KeyT key, Callable<AppendClientInfo> loader) throws Exception { + synchronized (this) { + AppendClientInfo info = appendCache.get(key, wrapWithPin(loader)); + info.pinAppendClient(); + return info; + } Review Comment:  Using `synchronized(this)` on the entire `getAndPin` method creates a global bottleneck for all cache accesses. Since the `loader` (which creates the `StreamAppendClient`) can be slow due to network calls, this will block all other threads trying to access the cache for different keys. Consider using a more granular locking mechanism, such as Guava's `Striped` locks, to allow concurrent access for different keys. ########## sdks/java/io/google-cloud-platform/src/main/java/org/apache/beam/sdk/io/gcp/bigquery/AppendClientInfo.java: ########## @@ -199,4 +219,32 @@ public TableRow toTableRow(ByteString protoBytes, Predicate<String> includeField throw new RuntimeException(e); } } + + public void pinAppendClient() { + BigQueryServices.StreamAppendClient client = + Preconditions.checkStateNotNull(getStreamAppendClient()); + client.pin(); + } + + public void unpinAppendClient(@Nullable ExecutorService executor) { + BigQueryServices.StreamAppendClient client = + Preconditions.checkStateNotNull(getStreamAppendClient()); + if (executor != null) { + runAsyncIgnoreFailure(executor, client::unpin); + } else { + client.unpin(); + } + } + + @SuppressWarnings({"FutureReturnValueIgnored"}) + private static void runAsyncIgnoreFailure(ExecutorService executor, ThrowingRunnable task) { + executor.submit( + () -> { + try { + task.run(); + } catch (Throwable e) { + LOG.info("Exception happened while executing async task. Ignoring: ", e); Review Comment:  Logging an exception at `INFO` level is unusual. Even if the failure is ignored, it is generally better to log it at `WARN` or `ERROR` level to make it more visible in logs when troubleshooting background tasks. ```suggestion LOG.warn("Exception happened while executing async task. Ignoring: ", e); ``` -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
