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The following commit(s) were added to refs/heads/branch_10_0 by this push:
new 331aa1e5ffe SOLR-17942: Raising configurable RAM per thread hard limit
using VarHandle (#3741)
331aa1e5ffe is described below
commit 331aa1e5ffe317678c04c3252b16639ca458e5b7
Author: Puneet Ahuja <[email protected]>
AuthorDate: Thu Dec 18 20:34:26 2025 +0530
SOLR-17942: Raising configurable RAM per thread hard limit using VarHandle
(#3741)
---
.../SOLR-17942-raising-ramPerThreadHardLimit.yml | 8 +++++
.../org/apache/solr/update/SolrIndexConfig.java | 37 +++++++++++++++++++++-
.../pages/index-segments-merging.adoc | 4 ++-
3 files changed, 47 insertions(+), 2 deletions(-)
diff --git
a/changelog/unreleased/puneet/SOLR-17942-raising-ramPerThreadHardLimit.yml
b/changelog/unreleased/puneet/SOLR-17942-raising-ramPerThreadHardLimit.yml
new file mode 100644
index 00000000000..e503e37c697
--- /dev/null
+++ b/changelog/unreleased/puneet/SOLR-17942-raising-ramPerThreadHardLimit.yml
@@ -0,0 +1,8 @@
+# See https://github.com/apache/solr/blob/main/dev-docs/changelog.adoc
+title: Raising the per ramPerThreadHardLimit to be configurable >2GB
+type: other # added, changed, fixed, deprecated, removed, dependency_update,
security, other
+authors:
+ - name: Puneet Ahuja
+links:
+ - name: SOLR-17942
+ url: https://issues.apache.org/jira/browse/SOLR-17942
diff --git a/solr/core/src/java/org/apache/solr/update/SolrIndexConfig.java
b/solr/core/src/java/org/apache/solr/update/SolrIndexConfig.java
index 236c9eb72bf..19a8e0135b9 100644
--- a/solr/core/src/java/org/apache/solr/update/SolrIndexConfig.java
+++ b/solr/core/src/java/org/apache/solr/update/SolrIndexConfig.java
@@ -20,6 +20,7 @@ import static
org.apache.solr.core.XmlConfigFile.assertWarnOrFail;
import java.io.IOException;
import java.lang.invoke.MethodHandles;
+import java.lang.invoke.VarHandle;
import java.util.Collections;
import java.util.Map;
import org.apache.lucene.analysis.Analyzer;
@@ -34,6 +35,7 @@ import org.apache.lucene.util.InfoStream;
import org.apache.solr.common.ConfigNode;
import org.apache.solr.common.MapSerializable;
import org.apache.solr.common.util.NamedList;
+import org.apache.solr.common.util.SuppressForbidden;
import org.apache.solr.core.DirectoryFactory;
import org.apache.solr.core.PluginInfo;
import org.apache.solr.core.SolrConfig;
@@ -246,7 +248,11 @@ public class SolrIndexConfig implements MapSerializable {
if (ramBufferSizeMB != -1) iwc.setRAMBufferSizeMB(ramBufferSizeMB);
if (ramPerThreadHardLimitMB != -1) {
- iwc.setRAMPerThreadHardLimitMB(ramPerThreadHardLimitMB);
+ if (ramPerThreadHardLimitMB > 2048) {
+ setPerThreadRAMLimitViaVarHandle(iwc, ramPerThreadHardLimitMB);
+ } else {
+ iwc.setRAMPerThreadHardLimitMB(ramPerThreadHardLimitMB);
+ }
}
if (maxCommitMergeWaitMillis > 0) {
@@ -346,4 +352,33 @@ public class SolrIndexConfig implements MapSerializable {
return scheduler;
}
+
+ @SuppressForbidden(reason = "Need to override Lucene's 2GB per-thread limit
for large datasets")
+ private static void setPerThreadRAMLimitViaVarHandle(IndexWriterConfig
config, int limitMB) {
+ MethodHandles.Lookup lookup = MethodHandles.lookup();
+ VarHandle fieldHandle = null;
+ Class<?> currentClass = config.getClass();
+
+ // Traverse the hierarchy to find the field
+ while (currentClass != null && fieldHandle == null) {
+ try {
+ MethodHandles.Lookup privateLookup =
MethodHandles.privateLookupIn(currentClass, lookup);
+ fieldHandle = privateLookup.findVarHandle(currentClass,
"perThreadHardLimitMB", int.class);
+ } catch (IllegalAccessException | NoSuchFieldException e) {
+ currentClass = currentClass.getSuperclass();
+ }
+ }
+
+ if (fieldHandle == null) {
+ log.error("Could not find VarHandle for perThreadHardLimitMB field");
+ return;
+ }
+
+ try {
+ fieldHandle.set(config, limitMB);
+ log.info("Set perThreadHardLimitMB to {} MB via VarHandle", limitMB);
+ } catch (RuntimeException | Error e) {
+ log.error("Failed to set per-thread RAM limit via VarHandle", e);
+ }
+ }
}
diff --git
a/solr/solr-ref-guide/modules/configuration-guide/pages/index-segments-merging.adoc
b/solr/solr-ref-guide/modules/configuration-guide/pages/index-segments-merging.adoc
index 3ffa49ef435..aa6a4985323 100644
---
a/solr/solr-ref-guide/modules/configuration-guide/pages/index-segments-merging.adoc
+++
b/solr/solr-ref-guide/modules/configuration-guide/pages/index-segments-merging.adoc
@@ -77,7 +77,7 @@ The default is `false`.
=== ramPerThreadHardLimitMB
Sets the maximum memory (defined in megabytes) consumption per thread
triggering a forced flush if exceeded.
-The given value must be greater than `0` and less than `2048` MB (2GB).
+The given value must be greater than `0`.
[source,xml]
----
@@ -86,6 +86,8 @@ The given value must be greater than `0` and less than `2048`
MB (2GB).
NOTE: This is an expert level parameter as it triggers forced flush even if
`ramBufferSizeMB` has not been exceeded.
+WARNING: Values greater than 2048 MB (2GB) will bypass Lucene's built-in limit
using reflection. This is an advanced feature that should only be used by
experienced administrators who understand the memory implications.
+
== Merging Index Segments
The following settings define when segments are merged.
