[jira] [Updated] (CURATOR-640) IllegalThreadStateException thrown when access PathChildrenCache in different thread groups

["Zili Chen (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/CURATOR-640?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Zili Chen updated CURATOR-640:
------------------------------
    Fix Version/s: 5.3.0

> IllegalThreadStateException thrown when access PathChildrenCache in different thread groups
> -------------------------------------------------------------------------------------------
>
>                 Key: CURATOR-640
>                 URL: https://issues.apache.org/jira/browse/CURATOR-640
>             Project: Apache Curator
>          Issue Type: Bug
>          Components: Recipes
>    Affects Versions: 5.2.1
>            Reporter: Xiaogang Shi
>            Assignee: Zili Chen
>            Priority: Minor
>             Fix For: 5.3.0
>
>          Time Spent: 50m
>  Remaining Estimate: 0h
>
> When we create PathChildrenCache instances without specifying thead factory, the {{defaultThreadFactory}} will be used to create threads. The {{defaultThreadFactory}} is typically backed by {{java.util.concurrent.DefaultThreadFactory}} which will add newly created threads into the thread group where it is instantiated. That is, the {{defaultThreadFactory}} will always add newly created threads into the first thread group that loads the {{PathChildrenCache}} class.
> In cases where {{PathChildrenCache}} is accessed in different thread groups, if the first thread group that load the {{PathChildrenCache}} is destroy, then all attempts to start the {{PathChildrenCache}} will fail.
> The problem can be reproduced using the following code: 
> {code:java}
> ThreadGroup threadGroup1 = new ThreadGroup("testGroup1");
> Thread thread1 = new Thread(threadGroup1, () -> {
>         PathChildrenCache cache1 =
>                 new PathChildrenCache(client, "/test1", true);
>         try {
>             cache1.start();
>             Thread.sleep(1000);
>         } catch (Throwable t) {
>             t.printStackTrace();
>         } finally {
>             try {
>                 cache1.close();
>             } catch (IOException e) {
>                 e.printStackTrace();
>             }
>         }
> });
> thread1.start();
> thread1.join();
> // After the thread group is destroyed, all PathChildrenCache instances 
> // will fail to start due to inability to add new threads into the first thread group
> threadGroup1.destroy();
> ThreadGroup threadGroup2 = new ThreadGroup("testGroup2");
> Thread thread2 = new Thread(threadGroup2, () -> {
>         PathChildrenCache cache2 =
>             new PathChildrenCache(client, "/test1", true);
>         try {
>             cache2.start();
>             Thread.sleep(1000);
>         } catch (Throwable t) {
>             t.printStackTrace();
>         } finally {
>             try {
>                 cache2.close();
>             } catch (IOException e) {
>                 e.printStackTrace();
>             }
>         }
> });
> thread2.start();
> thread2.join();
> {code}
> When starting {{cache2}}, the following exception is thrown:
> {code}
> java.lang.IllegalThreadStateException
> 	at java.base/java.lang.ThreadGroup.addUnstarted(ThreadGroup.java:892)
> 	at java.base/java.lang.Thread.<init>(Thread.java:434)
> 	at java.base/java.lang.Thread.<init>(Thread.java:708)
> 	at java.base/java.util.concurrent.Executors$DefaultThreadFactory.newThread(Executors.java:660)
> 	at org.apache.curator.shaded.com.google.common.util.concurrent.ThreadFactoryBuilder$1.newThread(ThreadFactoryBuilder.java:163)
> 	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.<init>(ThreadPoolExecutor.java:630)
> 	at java.base/java.util.concurrent.ThreadPoolExecutor.addWorker(ThreadPoolExecutor.java:920)
> 	at java.base/java.util.concurrent.ThreadPoolExecutor.execute(ThreadPoolExecutor.java:1353)
> 	at java.base/java.util.concurrent.Executors$DelegatedExecutorService.execute(Executors.java:721)
> 	at org.apache.curator.utils.CloseableExecutorService.submit(CloseableExecutorService.java:191)
> 	at org.apache.curator.framework.recipes.cache.PathChildrenCache.submitToExecutor(PathChildrenCache.java:841)
> 	at org.apache.curator.framework.recipes.cache.PathChildrenCache.offerOperation(PathChildrenCache.java:792)
> 	at org.apache.curator.framework.recipes.cache.PathChildrenCache.start(PathChildrenCache.java:300)
> 	at org.apache.curator.framework.recipes.cache.PathChildrenCache.start(PathChildrenCache.java:239)
> {code}



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