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https://issues.apache.org/jira/browse/CURATOR-640?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Zili Chen reassigned CURATOR-640:
---------------------------------
Assignee: Zili Chen
> 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
>
> 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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