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Posted to issues@zookeeper.apache.org by "maoling (Jira)" <ji...@apache.org> on 2020/11/01 06:08:00 UTC
[jira] [Commented] (ZOOKEEPER-3986) ConcurrentModificationException
in PrepRequestProcessor.checkACL
[ https://issues.apache.org/jira/browse/ZOOKEEPER-3986?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17224223#comment-17224223 ]
maoling commented on ZOOKEEPER-3986:
------------------------------------
[~jhalterman] I had reproduced this issue in the branch-3.5. Are you free to provide a patch against?
A code snippet:
{code:java}
public static void main(String[] args) {
// only use one zk client to have the same ServerCnxn instance.
final ZooKeeper zk = createClient();
// make sure you have the path:/10-31-2 and use the CLI:
// [zk: 127.0.0.1:2180(CONNECTED) 1] addauth digest user1:12345
// [zk: 127.0.0.1:2180(CONNECTED) 2] getAcl /10-31-2
// 'digest,'user1:+owfoSBn/am19roBPzR1/MfCblE=
// : cdrwa
String path = "/10-31-2";
try {
//one thread
new Thread(new Runnable() {
@Override
public void run() {
zk.addAuthInfo("digest", "user1:12345".getBytes());
Random r = new Random(1);
for (int i = 0; i < 10000; i++) {
zk.addAuthInfo("digest", ("maoling" + r.nextInt(1000000) + "_" + System.currentTimeMillis() + ":12345").getBytes());
}
while (true) {
try {
System.out.println(zk.getChildren(path, null, new Stat()));
Thread.sleep(500);
} catch (KeeperException | InterruptedException e) {
e.printStackTrace();
}
}
}
}).start();
//anothor thread
new Thread(new Runnable() {
@Override
public void run() {
Random r = new Random(1);
while (true) {
try {
String id = "gaki" + r.nextInt(10000000) + "_" + r.nextInt(10000) + "_" + System.currentTimeMillis() + ":12345";
zk.addAuthInfo("digest", id.getBytes());
Thread.sleep(500);
} catch (Exception e) {
e.printStackTrace();
}
}
}
}).start();
} catch (Exception e) {
e.printStackTrace();
}
}
{code}
> ConcurrentModificationException in PrepRequestProcessor.checkACL
> ----------------------------------------------------------------
>
> Key: ZOOKEEPER-3986
> URL: https://issues.apache.org/jira/browse/ZOOKEEPER-3986
> Project: ZooKeeper
> Issue Type: Bug
> Components: server
> Affects Versions: 3.5.0
> Reporter: Jonathan Halterman
> Priority: Major
>
> We have some Zookeeper clusters under pretty heavy load that are occasionally throwing ConcurrentModificationException during ACL checking:
> {noformat}
>
> ERROR [CommitProcWorkThread-17:FinalRequestProcessor@439] - Failed to process sessionid:0xa006cd06b181510 type:getChildren2 cxid:0x4dae zxid:0xfffffffffffffffe txntype:unknown reqpath:n/a
> java.util.ConcurrentModificationException
> at java.util.ArrayList$Itr.checkForComodification(ArrayList.java:909)
> at java.util.ArrayList$Itr.next(ArrayList.java:859)
> at java.util.Collections$UnmodifiableCollection$1.next(Collections.java:1044)
> at org.apache.zookeeper.server.PrepRequestProcessor.checkACL(PrepRequestProcessor.java:321)
> at org.apache.zookeeper.server.FinalRequestProcessor.processRequest(FinalRequestProcessor.java:383)
> at org.apache.zookeeper.server.quorum.CommitProcessor$CommitWorkRequest.doWork(CommitProcessor.java:297)
> at org.apache.zookeeper.server.WorkerService$ScheduledWorkRequest.run(WorkerService.java:162)
> at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
> at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
> at java.lang.Thread.run(Thread.java:748)
> {noformat}
> This appears to be caused by auths changing while we're processing a request, such as here:
> [https://github.com/apache/zookeeper/blob/branch-3.5/zookeeper-server/src/main/java/org/apache/zookeeper/server/ServerCnxn.java#L101-L110]
> The result of this appears to be that occasionally requests fail unexpectedly.
>
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