Hi Shalini,

I’ve seen this kind of issue before, and it usually points to a replica in the 
SolrCloud cluster getting overloaded or pausing long enough for distributed 
updates to time out. In your case, the shard2 replica 
(sitecore_master_index_shard2_replica_n16) looks like it’s stalling for over 20 
seconds, even though the update queue itself is technically empty. 

That normally happens when the node is under heavy load, has slow disk I/O 
during merges, or is hitting long JVM GC pauses due to low heap or memory 
pressure.

The first thing I’d check is the Solr logs on that specific replica around the 
same timestamp, along with the GC logs, because if the JVM heap is too small 
and GC pauses are too long, Solr will freeze just enough to trigger the “task 
queue stalled” error. 

Also worth checking if the replica is healthy in the SolrCloud UI, or if it’s 
sitting in a state like “recovering” or “down,” because that can cause the same 
behavior.

If this problem keeps repeating, increasing the Xmx heap on that node usually 
stabilizes it. To do that, open the Solr startup config on the affected node. 
If you’re running the standard service install, it’s usually under solr.in.sh 
(Linux) or solr.in.cmd (Windows). Look for the line that sets the memory, 
something like:

SOLR_JAVA_MEM="-Xms4g -Xmx4g"

You can raise the max heap by increasing the value of -Xmx, for example:

SOLR_JAVA_MEM="-Xms4g -Xmx8g"

You should also take a look at the actual size of the replica on disk and 
adjust the Xmx based on that. As a rule of thumb, the JVM heap should be sized 
to comfortably handle the index segment merges, so matching Xmx to the size of 
the replica index usually gives the best stability. If the heap is too small 
compared to the index size, you’re almost guaranteed to hit long GC pauses or 
stalled update tasks.

After updating the file, restart Solr on that node so the new heap size takes 
effect. Just make sure the machine actually has enough physical RAM available; 
otherwise GC issues will just move elsewhere.

Hope this helps,
Cip

Opensolr.com
Your Path to AI Search 
<https://opensolr.com/faq/view/web-crawler/46/Opensolr-Web-Crawler-Site-Search-Solution>
[email protected] <mailto:[email protected]>
https://opensolr.com <https://opensolr.com/>
VAT: RO-35410526




> On 2 Dec 2025, at 18:47, Dulasiraj, Shalini via users <[email protected]> 
> wrote:
> 
> Hi Everyone,
> We are using SolrCloud 8.11.2 integrated with Sitecore 10.4, and we are 
> facing an intermittent indexing issue in master index whenever certain items 
> are created in Sitecore.
> 
> In the logs, we are seeing the following error:
> Task queue processing has stalled for 20085 ms with 0 remaining elements to 
> process.
> 
> Has anyone experienced a similar issue or have any suggestions on how to fix 
> this timeout issue?
> I appreciate any guidance or insights.
> 
> Complete Error:
> 2025-10-09 21:02:19.537 ERROR (qtp1420232606-314828) [c:sitecore_master_index 
> s:shard1 r:core_node3 x:sitecore_master_index_shard1_replica_n1] 
> o.a.s.s.HttpSolrCall 
> org.apache.solr.update.processor.DistributedUpdateProcessor$DistributedUpdatesAsyncException:
>  Async exception during distributed update: Error from server at 
> https://wep3-prod104-solr1.avndscxom.com:8983/solr/sitecore_master_index_shard2_replica_n16/:
>  Server Error
> 
> request: 
> https://wep3-prod104-solr1.avndscxom.com:8983/solr/sitecore_master_index_shard2_replica_n16/
> Remote error message: Task queue processing has stalled for 20085 ms with 0 
> remaining elements to process. => 
> org.apache.solr.update.processor.DistributedUpdateProcessor$DistributedUpdatesAsyncException:
>  Async exception during distributed update: Error from server at 
> https://wep3-prod104-solr1.avndscxom.com:8983/solr/sitecore_master_index_shard2_replica_n16/:
>  Server Error
> 
> request: 
> https://wep3-prod104-solr1.avndscxom.com:8983/solr/sitecore_master_index_shard2_replica_n16/
> Remote error message: Task queue processing has stalled for 20085 ms with 0 
> remaining elements to process.
>              at 
> org.apache.solr.update.processor.DistributedZkUpdateProcessor.doDistribFinish(DistributedZkUpdateProcessor.java:1193)
> org.apache.solr.update.processor.DistributedUpdateProcessor$DistributedUpdatesAsyncException:
>  Async exception during distributed update: Error from server at 
> https://wep3-prod104-solr1.avndscxom.com:8983/solr/sitecore_master_index_shard2_replica_n16/:
>  Server Error
> 
> request: 
> https://wep3-prod104-solr1.avndscxom.com:8983/solr/sitecore_master_index_shard2_replica_n16/
> Remote error message: Task queue processing has stalled for 20085 ms with 0 
> remaining elements to process.
>              at 
> org.apache.solr.update.processor.DistributedZkUpdateProcessor.doDistribFinish(DistributedZkUpdateProcessor.java:1193)
>  ~[solr-core-8.11.2.jar:8.11.2 17dee71932c683e345508113523e764c3e4c80fa - 
> mdrob - 2022-06-13 11:27:54]
>              at 
> org.apache.solr.update.processor.DistributedUpdateProcessor.finish(DistributedUpdateProcessor.java:1122)
>  ~[solr-core-8.11.2.jar:8.11.2 17dee71932c683e345508113523e764c3e4c80fa - 
> mdrob - 2022-06-13 11:27:54]
>              at 
> org.apache.solr.update.processor.LogUpdateProcessorFactory$LogUpdateProcessor.finish(LogUpdateProcessorFactory.java:195)
>  ~[solr-core-8.11.2.jar:8.11.2 17dee71932c683e345508113523e764c3e4c80fa - 
> mdrob - 2022-06-13 11:27:54]
>              at 
> org.apache.solr.update.processor.UpdateRequestProcessor.finish(UpdateRequestProcessor.java:80)
>  ~[solr-core-8.11.2.jar:8.11.2 17dee71932c683e345508113523e764c3e4c80fa - 
> mdrob - 2022-06-13 11:27:54]
>              at 
> org.apache.solr.update.processor.UpdateRequestProcessor.finish(UpdateRequestProcessor.java:80)
>  ~[solr-core-8.11.2.jar:8.11.2 17dee71932c683e345508113523e764c3e4c80fa - 
> mdrob - 2022-06-13 11:27:54]
>              at 
> org.apache.solr.update.processor.UpdateRequestProcessor.finish(UpdateRequestProcessor.java:80)
>  ~[solr-core-8.11.2.jar:8.11.2 17dee71932c683e345508113523e764c3e4c80fa - 
> mdrob - 2022-06-13 11:27:54]
>              at 
> org.apache.solr.update.processor.UpdateRequestProcessor.finish(UpdateRequestProcessor.java:80)
>  ~[solr-core-8.11.2.jar:8.11.2 17dee71932c683e345508113523e764c3e4c80fa - 
> mdrob - 2022-06-13 11:27:54]
>              at 
> org.apache.solr.update.processor.UpdateRequestProcessor.finish(UpdateRequestProcessor.java:80)
>  ~[solr-core-8.11.2.jar:8.11.2 17dee71932c683e345508113523e764c3e4c80fa - 
> mdrob - 2022-06-13 11:27:54]
>              at 
> org.apache.solr.update.processor.UpdateRequestProcessor.finish(UpdateRequestProcessor.java:80)
>  ~[solr-core-8.11.2.jar:8.11.2 17dee71932c683e345508113523e764c3e4c80fa - 
> mdrob - 2022-06-13 11:27:54]
>              at 
> org.apache.solr.update.processor.UpdateRequestProcessor.finish(UpdateRequestProcessor.java:80)
>  ~[solr-core-8.11.2.jar:8.11.2 17dee71932c683e345508113523e764c3e4c80fa - 
> mdrob - 2022-06-13 11:27:54]
>              at 
> org.apache.solr.update.processor.UpdateRequestProcessor.finish(UpdateRequestProcessor.java:80)
>  ~[solr-core-8.11.2.jar:8.11.2 17dee71932c683e345508113523e764c3e4c80fa - 
> mdrob - 2022-06-13 11:27:54]
>              at 
> org.apache.solr.handler.ContentStreamHandlerBase.handleRequestBody(ContentStreamHandlerBase.java:92)
>  ~[solr-core-8.11.2.jar:8.11.2 17dee71932c683e345508113523e764c3e4c80fa - 
> mdrob - 2022-06-13 11:27:54]
>              at 
> org.apache.solr.handler.RequestHandlerBase.handleRequest(RequestHandlerBase.java:216)
>  ~[solr-core-8.11.2.jar:8.11.2 17dee71932c683e345508113523e764c3e4c80fa - 
> mdrob - 2022-06-13 11:27:54]
>              at org.apache.solr.core.SolrCore.execute(SolrCore.java:2637) 
> ~[solr-core-8.11.2.jar:8.11.2 17dee71932c683e345508113523e764c3e4c80fa - 
> mdrob - 2022-06-13 11:27:54]
>              at 
> org.apache.solr.servlet.HttpSolrCall.execute(HttpSolrCall.java:791) 
> ~[solr-core-8.11.2.jar:8.11.2 17dee71932c683e345508113523e764c3e4c80fa - 
> mdrob - 2022-06-13 11:27:54]
>              at 
> org.apache.solr.servlet.HttpSolrCall.call(HttpSolrCall.java:564) 
> ~[solr-core-8.11.2.jar:8.11.2 17dee71932c683e345508113523e764c3e4c80fa - 
> mdrob - 2022-06-13 11:27:54]
>              at 
> org.apache.solr.servlet.SolrDispatchFilter.doFilter(SolrDispatchFilter.java:427)
>  ~[solr-core-8.11.2.jar:8.11.2 17dee71932c683e345508113523e764c3e4c80fa - 
> mdrob - 2022-06-13 11:27:54]
>              at 
> org.apache.solr.servlet.SolrDispatchFilter.doFilter(SolrDispatchFilter.java:357)
>  ~[solr-core-8.11.2.jar:8.11.2 17dee71932c683e345508113523e764c3e4c80fa - 
> mdrob - 2022-06-13 11:27:54]
>              at 
> org.eclipse.jetty.servlet.FilterHolder.doFilter(FilterHolder.java:201) 
> ~[jetty-servlet-9.4.44.v20210927.jar:9.4.44.v20210927]
>              at 
> org.eclipse.jetty.servlet.ServletHandler$Chain.doFilter(ServletHandler.java:1601)
>  ~[jetty-servlet-9.4.44.v20210927.jar:9.4.44.v20210927]
>              at 
> org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:548) 
> ~[jetty-servlet-9.4.44.v20210927.jar:9.4.44.v20210927]
>              at 
> org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:143) 
> ~[jetty-server-9.4.44.v20210927.jar:9.4.44.v20210927]
>              at 
> org.eclipse.jetty.security.SecurityHandler.handle(SecurityHandler.java:600) 
> ~[jetty-security-9.4.44.v20210927.jar:9.4.44.v20210927]
>              at 
> org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:127)
>  ~[jetty-server-9.4.44.v20210927.jar:9.4.44.v20210927]
>              at 
> org.eclipse.jetty.server.handler.ScopedHandler.nextHandle(ScopedHandler.java:235)
>  ~[jetty-server-9.4.44.v20210927.jar:9.4.44.v20210927]
>              at 
> org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:1624)
>  ~[jetty-server-9.4.44.v20210927.jar:9.4.44.v20210927]
>              at 
> org.eclipse.jetty.server.handler.ScopedHandler.nextHandle(ScopedHandler.java:233)
>  ~[jetty-server-9.4.44.v20210927.jar:9.4.44.v20210927]
>              at 
> org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1434)
>  ~[jetty-server-9.4.44.v20210927.jar:9.4.44.v20210927]
>              at 
> org.eclipse.jetty.server.handler.ScopedHandler.nextScope(ScopedHandler.java:188)
>  ~[jetty-server-9.4.44.v20210927.jar:9.4.44.v20210927]
>              at 
> org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:501) 
> ~[jetty-servlet-9.4.44.v20210927.jar:9.4.44.v20210927]
>              at 
> org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:1594)
>  ~[jetty-server-9.4.44.v20210927.jar:9.4.44.v20210927]
>              at 
> org.eclipse.jetty.server.handler.ScopedHandler.nextScope(ScopedHandler.java:186)
>  ~[jetty-server-9.4.44.v20210927.jar:9.4.44.v20210927]
>              at 
> org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1349)
>  ~[jetty-server-9.4.44.v20210927.jar:9.4.44.v20210927]
>              at 
> org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:141) 
> ~[jetty-server-9.4.44.v20210927.jar:9.4.44.v20210927]
>              at 
> org.eclipse.jetty.server.handler.ContextHandlerCollection.handle(ContextHandlerCollection.java:191)
>  ~[jetty-server-9.4.44.v20210927.jar:9.4.44.v20210927]
>              at 
> org.eclipse.jetty.server.handler.InetAccessHandler.handle(InetAccessHandler.java:177)
>  ~[jetty-server-9.4.44.v20210927.jar:9.4.44.v20210927]
>              at 
> org.eclipse.jetty.server.handler.HandlerCollection.handle(HandlerCollection.java:146)
>  ~[jetty-server-9.4.44.v20210927.jar:9.4.44.v20210927]
>              at 
> org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:127)
>  ~[jetty-server-9.4.44.v20210927.jar:9.4.44.v20210927]
>              at 
> org.eclipse.jetty.rewrite.handler.RewriteHandler.handle(RewriteHandler.java:322)
>  ~[jetty-rewrite-9.4.44.v20210927.jar:9.4.44.v20210927]
>              at 
> org.eclipse.jetty.server.handler.gzip.GzipHandler.handle(GzipHandler.java:763)
>  ~[jetty-server-9.4.44.v20210927.jar:9.4.44.v20210927]
>              at 
> org.eclipse.jetty.server.handler.StatisticsHandler.handle(StatisticsHandler.java:179)
>  ~[jetty-server-9.4.44.v20210927.jar:9.4.44.v20210927]
>              at 
> org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:127)
>  ~[jetty-server-9.4.44.v20210927.jar:9.4.44.v20210927]
>              at org.eclipse.jetty.server.Server.handle(Server.java:516) 
> ~[jetty-server-9.4.44.v20210927.jar:9.4.44.v20210927]
>              at 
> org.eclipse.jetty.server.HttpChannel.lambda$handle$1(HttpChannel.java:400) 
> ~[jetty-server-9.4.44.v20210927.jar:9.4.44.v20210927]
>              at 
> org.eclipse.jetty.server.HttpChannel.dispatch(HttpChannel.java:645) 
> ~[jetty-server-9.4.44.v20210927.jar:9.4.44.v20210927]
>              at 
> org.eclipse.jetty.server.HttpChannel.handle(HttpChannel.java:392) 
> ~[jetty-server-9.4.44.v20210927.jar:9.4.44.v20210927]
>              at 
> org.eclipse.jetty.server.HttpConnection.onFillable(HttpConnection.java:277) 
> ~[jetty-server-9.4.44.v20210927.jar:9.4.44.v20210927]
>              at 
> org.eclipse.jetty.io.AbstractConnection$ReadCallback.succeeded(AbstractConnection.java:311)
>  ~[jetty-io-9.4.44.v20210927.jar:9.4.44.v20210927]
>              at 
> org.eclipse.jetty.io.FillInterest.fillable(FillInterest.java:105) 
> ~[jetty-io-9.4.44.v20210927.jar:9.4.44.v20210927]
>              at 
> org.eclipse.jetty.io.ssl.SslConnection$DecryptedEndPoint.onFillable(SslConnection.java:555)
>  ~[jetty-io-9.4.44.v20210927.jar:9.4.44.v20210927]
>              at 
> org.eclipse.jetty.io.ssl.SslConnection.onFillable(SslConnection.java:410) 
> ~[jetty-io-9.4.44.v20210927.jar:9.4.44.v20210927]
>              at 
> org.eclipse.jetty.io.ssl.SslConnection$2.succeeded(SslConnection.java:164) 
> ~[jetty-io-9.4.44.v20210927.jar:9.4.44.v20210927]
>              at 
> org.eclipse.jetty.io.FillInterest.fillable(FillInterest.java:105) 
> ~[jetty-io-9.4.44.v20210927.jar:9.4.44.v20210927]
>              at 
> org.eclipse.jetty.io.ChannelEndPoint$1.run(ChannelEndPoint.java:104) 
> ~[jetty-io-9.4.44.v20210927.jar:9.4.44.v20210927]
>              at 
> org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.runTask(EatWhatYouKill.java:338)
>  ~[jetty-util-9.4.44.v20210927.jar:9.4.44.v20210927]
>              at 
> org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.doProduce(EatWhatYouKill.java:315)
>  ~[jetty-util-9.4.44.v20210927.jar:9.4.44.v20210927]
>              at 
> org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.tryProduce(EatWhatYouKill.java:173)
>  ~[jetty-util-9.4.44.v20210927.jar:9.4.44.v20210927]
>              at 
> org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.run(EatWhatYouKill.java:131)
>  ~[jetty-util-9.4.44.v20210927.jar:9.4.44.v20210927]
>              at 
> org.eclipse.jetty.util.thread.ReservedThreadExecutor$ReservedThread.run(ReservedThreadExecutor.java:409)
>  ~[jetty-util-9.4.44.v20210927.jar:9.4.44.v20210927]
>              at 
> org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:883)
>  ~[jetty-util-9.4.44.v20210927.jar:9.4.44.v20210927]
>              at 
> org.eclipse.jetty.util.thread.QueuedThreadPool$Runner.run(QueuedThreadPool.java:1034)
>  ~[jetty-util-9.4.44.v20210927.jar:9.4.44.v20210927]
>              at java.lang.Thread.run(Unknown Source) [?:1.8.0_271]
> 
> 
> Regards,
> Shalini D
> 
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