#1962 ✓resolved
Andrei Solntsev

Getting Static Initialization Deadlock in class DataParser

Reported by Andrei Solntsev | June 30th, 2015 @ 12:12 PM | in 1.3.2 (closed)

Sometimes we get Static Initialization Deadlock after starting server.
The problem is in DataBinder class that
1) has static initialization block (which is synchronized on JVM level), and
2) references all its subclasses (that is bad practice in OOP)

The problem happens, when 2 different threads use DataBinder and one of its subclasses (UrlEncodedParser) at the same moment. Then UrlEncodedParser waits until DataParser class is initialized, but DataParser waits until UrlEncodedParser class is initialized. We get deadlock.

Framework version: 1.3.x
Platform you're using: Java 8, Linux

Reproduction steps: start play server

Details: many threaded stay in "Runnable" status for a long time. But actually they do not work, but waiting for something:

"play-thread-30" #192 prio=5 os_prio=0 tid=0x00007ffa20001800 nid=0x26a9 in Object.wait() [0x00007ff9a44c8000]
   java.lang.Thread.State: RUNNABLE
    at play.mvc.ActionInvoker.invoke(ActionInvoker.java:116)
"play-thread-1" #163 prio=5 os_prio=0 tid=0x00007ffa78008800 nid=0x2682 in Object.wait() [0x00007ff9a63e5000]
   java.lang.Thread.State: RUNNABLE
    at play.data.parsing.DataParser.<clinit>(DataParser.java:18)
    at play.mvc.Scope$Params.checkAndParse(Scope.java:365)
    at play.mvc.Scope$Params.all(Scope.java:463)
    at play.modules.logger.RequestLogPlugin.extractParams(RequestLogPlugin.java:103)

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