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https://issues.apache.org/jira/browse/NIFI-5501?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16895026#comment-16895026
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Przemyslaw Dubaniewicz commented on NIFI-5501:
----------------------------------------------
I had the same problem with newer JDBC driver from Oracle:
{code:java}
"mysql-cj-abandoned-connection-cleanup" #124 daemon prio=5 os_prio=0
tid=0x00007f7108085000 nid=0x46b in Object.wait() [0x00007f70d2262000]
java.lang.Thread.State: TIMED_WAITING (on object monitor)
at java.lang.Object.wait(Native Method)
at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:144)
- locked <0x00000005c4c05c40> (a java.lang.ref.ReferenceQueue$Lock)
at
com.mysql.cj.jdbc.AbandonedConnectionCleanupThread.run(AbandonedConnectionCleanupThread.java:85)
at
java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at java.lang.Thread.run(Thread.java:748) {code}
It seems the problem is caused by this old MySQL JDBC bug, which is still not
fixed.
I switched to MariaDB JDBC driver and I have no more threads leaking.
> MySQL connection cleanup thread leak
> ------------------------------------
>
> Key: NIFI-5501
> URL: https://issues.apache.org/jira/browse/NIFI-5501
> Project: Apache NiFi
> Issue Type: Bug
> Components: Core Framework
> Affects Versions: 1.7.1
> Environment: - Ubuntu 18.04 LTS
> - mysql-connector-java-5.1.46
> - Java 1.8.0_171
> Reporter: Tanapol Nearunchorn
> Priority: Major
> Attachments: nifi-threaddump.txt
>
>
> There are thousands of "Abandoned connection cleanup thread" left running
> that cause memory leak in NiFi.
> I got a thread dump example here (full thread dump also attached):
> {code:java}
> "Abandoned connection cleanup thread" #18371 daemon prio=5 os_prio=0
> tid=0x00007f3b840e7800 nid=0x76a3 in Object.wait() [0x00007f3b24ebb000]
> java.lang.Thread.State: TIMED_WAITING (on object monitor)
> at java.lang.Object.wait(Native Method)
> at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:143)
> - locked <0x0000000348a12628> (a java.lang.ref.ReferenceQueue$Lock)
> at
> com.mysql.jdbc.AbandonedConnectionCleanupThread.run(AbandonedConnectionCleanupThread.java:64)
> at
> java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
> at
> java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
> at java.lang.Thread.run(Thread.java:748)
> Locked ownable synchronizers:
> - <0x0000000348a12648> (a java.util.concurrent.ThreadPoolExecutor$Worker)
> {code}
> I'm not sure where these threads come from which component because in my
> flow, I used CaptureChangeMySQL processor and DBCPConnectionPool controller
> service.
> As I also found related problem here: [mysql Bug
> #69526|https://bugs.mysql.com/bug.php?id=69526] but it quite a bit old.
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