[jboss-jira] [JBoss JIRA] (WFLY-3620) Deadlock while logging

[Stefan Schueffler (JIRA)]

Stefan Schueffler created WFLY-3620:
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             Summary: Deadlock while logging
                 Key: WFLY-3620
                 URL: https://issues.jboss.org/browse/WFLY-3620
             Project: WildFly
          Issue Type: Bug
      Security Level: Public (Everyone can see)
          Components: Logging
    Affects Versions: 8.1.0.Final
         Environment: CentOS 6.5 64bit, java7u45 64bit (and 32 bit, the same behavior)
            Reporter: Stefan Schueffler
            Assignee: James Perkins
            Priority: Critical


We hit really often a deadlock? in org.jboss.stdio.StdioContext$DelegatingPrintStream.println(StdioContext.java:474)

Even if the "StdioContext" belongs to Jboss-Logging, the problem occurs in our production wildfly installation twice to 4 times a day - all threads are deadlocking while trying to log.debug, log.error, or (sometimes) System.out.println from our application code, and wildfly does not respond anymore...

The partial stacktrace always is similar to this one:
{code}
 "default task-64" prio=10 tid=0x4c539c00 nid=0x5ef9 waiting for monitor entry [0x495e0000]
   java.lang.Thread.State: BLOCKED (on object monitor)
        at java.io.PrintStream.println(PrintStream.java:806)
        - waiting to lock <0x5ee0adf8> (a java.io.PrintStream)
        at org.jboss.stdio.StdioContext$DelegatingPrintStream.println(StdioContext.java:474)
        at jsp.communications.statuschange.selectStatus_jsp._jspService(selectStatus_jsp.java:413)
        at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:69)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:790)
        at io.undertow.servlet.handlers.ServletHandler.handleRequest(ServletHandler.java:85)
        at io.undertow.servlet.handlers.FilterHandler.handleRequest(FilterHandler.java:82)
{code}

While investigating the StdioContext - class, i really wondered whether the used "locking/checking by using a threadlocal" could have worked in a multi-threaded environment (it should have the very same problems as every "double checking" algorithm without proper synchronization).

If all threads are hanging in this particular lock, only a full wildfly-restart recovers in our case.

My preferred solution would be a rework of the used org.jboss.stdio. classes, as the used idioms of ThreadLocals for reentrant-checks are at least highly unusual?



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