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https://issues.apache.org/jira/browse/SOLR-13896?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16993281#comment-16993281
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ASF subversion and git services commented on SOLR-13896:
--------------------------------------------------------
Commit c4f0c3363828c088eefa2b99783178848c2f1f7a in lucene-solr's branch
refs/heads/gradle-master from Andrzej Bialecki
[ https://gitbox.apache.org/repos/asf?p=lucene-solr.git;h=c4f0c33 ]
SOLR-13975, SOLR-13896: ConcurrentUpdateSolrClient connection stall prevention.
> Paused a non-leader node can cause recovery on other nodes
> ----------------------------------------------------------
>
> Key: SOLR-13896
> URL: https://issues.apache.org/jira/browse/SOLR-13896
> Project: Solr
> Issue Type: Bug
> Security Level: Public(Default Security Level. Issues are Public)
> Reporter: Cao Manh Dat
> Assignee: Andrzej Bialecki
> Priority: Major
> Attachments: SOLR-13896.patch
>
>
> All stacktraces below based on 7.5 branch. This problem still exist at 8.x
> branches. Here is the scenario, we have 3 replicas
> * L: the leader replica
> * R: the normal replica
> * P: the poor one which was paused then resumed
> L is trying to send data to R, P during that P get paused, here is what
> happen at L's threads.
> * Thread 1 is stucking at this line of StreamingSolrClients
> {code:java}
> public synchronized void blockUntilFinished() {
> for (ConcurrentUpdateSolrClient client : solrClients.values()) {
> client.blockUntilFinished();
> }
> } {code}
> basically this thread is trying to wait for other sender threads to finish.
> Let's assume that this is the content of *solrClients.values : [clientToP,
> clientToR]*
> * Thread 2 coressponds to *clientToP* since P is paused, it doesn't close
> the connection. it just keep the connection and never return any data backs
> to L. So this thread stuck with this stack trace, waiting for response data
> from *P* (with timeout=600000ms)*.* Therefore it cause the thread1 stuck at
> *clientToP.blockUntilFinished()*
> {code:java}
> java.lang.Thread.State: RUNNABLE java.lang.Thread.State: RUNNABLE at
> java.net.SocketInputStream.socketRead0(Native Method) at
> java.net.SocketInputStream.socketRead(SocketInputStream.java:116) at
> java.net.SocketInputStream.read(SocketInputStream.java:171) at
> java.net.SocketInputStream.read(SocketInputStream.java:141) at
> org.apache.http.impl.io.SessionInputBufferImpl.streamRead(SessionInputBufferImpl.java:137)
> at
> org.apache.http.impl.io.SessionInputBufferImpl.fillBuffer(SessionInputBufferImpl.java:153)
> at
> org.apache.http.impl.io.SessionInputBufferImpl.readLine(SessionInputBufferImpl.java:282)
> at
> org.apache.http.impl.conn.DefaultHttpResponseParser.parseHead(DefaultHttpResponseParser.java:138)
> at
> org.apache.http.impl.conn.DefaultHttpResponseParser.parseHead(DefaultHttpResponseParser.java:56)
> at
> org.apache.http.impl.io.AbstractMessageParser.parse(AbstractMessageParser.java:259)
> at
> org.apache.http.impl.DefaultBHttpClientConnection.receiveResponseHeader(DefaultBHttpClientConnection.java:163)
> at
> org.apache.http.impl.conn.CPoolProxy.receiveResponseHeader(CPoolProxy.java:165)
> at
> org.apache.http.protocol.HttpRequestExecutor.doReceiveResponse(HttpRequestExecutor.java:273)
> at
> org.apache.http.protocol.HttpRequestExecutor.execute(HttpRequestExecutor.java:125)
> at
> org.apache.solr.util.stats.InstrumentedHttpRequestExecutor.execute(InstrumentedHttpRequestExecutor.java:120)
> at
> org.apache.http.impl.execchain.MainClientExec.execute(MainClientExec.java:272)
> at
> org.apache.http.impl.execchain.ProtocolExec.execute(ProtocolExec.java:185) at
> org.apache.http.impl.execchain.RetryExec.execute(RetryExec.java:89) at
> org.apache.http.impl.execchain.RedirectExec.execute(RedirectExec.java:111) at
> org.apache.http.impl.client.InternalHttpClient.doExecute(InternalHttpClient.java:185)
> at
> org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:83)
> at
> org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:56)
> at
> org.apache.solr.client.solrj.impl.ConcurrentUpdateSolrClient$Runner.sendUpdateStream(ConcurrentUpdateSolrClient.java:347){code}
> * Since *clientToR* is the second element of the array, is never get
> called (or at least after the timeout). This problem cause Thread 3, to stuck
> at this line
> {code:java}
> upd = queue.poll(pollQueueTime, TimeUnit.MILLISECONDS); {code}
> note that pollQueueTime == Integer.MAX_VALUE (this set by
> StreamingSolrClients). Therefore unless clientToR.blockUntilFinished() is
> called (which interrupt Thread 3) this Thread 3 will stuck at above line
> forever
> * because *clientToR* is sending data to R but never close the outputstream,
> so basically R just waiting forever (until timeout at 120000ms later). Which
> then lead to this exception
> {code:java}
> o.a.s.h.RequestHandlerBase java.io.IOException:
> java.util.concurrent.TimeoutException: Idle timeout expired: 120003/120000
> mso.a.s.h.RequestHandlerBase java.io.IOException:
> java.util.concurrent.TimeoutException: Idle timeout expired: 120003/120000 ms
> at
> org.eclipse.jetty.server.HttpInput$ErrorState.noContent(HttpInput.java:1080)
> at org.eclipse.jetty.server.HttpInput.read(HttpInput.java:313) at
> org.apache.solr.servlet.ServletInputStreamWrapper.read(ServletInputStreamWrapper.java:74)
> at
> org.apache.commons.io.input.ProxyInputStream.read(ProxyInputStream.java:100)
> at
> org.apache.solr.common.util.FastInputStream.readWrappedStream(FastInputStream.java:79)
> at
> org.apache.solr.common.util.FastInputStream.refill(FastInputStream.java:88)
> at org.apache.solr.common.util.FastInputStream.peek(FastInputStream.java:60)
> at
> org.apache.solr.handler.loader.JavabinLoader.parseAndLoadDocs(JavabinLoader.java:107)
> at org.apache.solr.handler.loader.JavabinLoader.load(JavabinLoader.java:55)
> {code}
> * After that the leader put all replicas including none-paused one to
> recovery
>
> It is a very bad outcome and, this is not just theoretical problem since some
> cloud platforms can freeze a node when doing maintenance.
> Thanks [~ab] and [~shalin] on helping me debugging this problem.
>
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