100% CPU usage after resume WinXP from stand-by: appears to be in MINA

• Key: DIRSERVER-608
• Type: Bug
• Status: Closed
• Resolution: Duplicate
• Priority: Major
• Assignee: Trustin Lee
• Reporter: Norval Hope
• Component/s: core
• Affects Version/s: 1.0-RC1

Description

I've noticed that when ApacheDS is running on my laptop and I close the lid and later open it that the ApacheDS java process is using 100% CPU. When logging at the DEBUG level the 100% CPU usage seems to coincide with messages like this (the 20 second periodic sync):

============================
2006-04-19 12:46:08,833 101464 [SynchWorkerThread] (org.apache.directory.shared.ldap.name.DnParser:184) DEBUG org.apache.directory.shared.ldap.name.DnParser - Parsing DN 'ou=system'
2006-04-19 12:46:08,883 101514 [SynchWorkerThread] (org.apache.directory.shared.ldap.name.DnParser:184) DEBUG org.apache.directory.shared.ldap.name.DnParser - Parsing DN 'uid=admin,ou=system'
2006-04-19 12:46:08,943 101574 [SynchWorkerThread] (org.apache.directory.shared.ldap.name.DnParser:184) DEBUG org.apache.directory.shared.ldap.name.DnParser - Parsing DN 'uid=admin,ou=system'
2006-04-19 12:46:09,013 101644 [SynchWorkerThread] (org.apache.directory.server.core.authn.AuthenticationService:248) DEBUG org.apache.directory.server.core.authn.AuthenticationService - Testing if entry name = 'ou=system' exists
2006-04-19 12:46:09,063 101694 [SynchWorkerThread] (org.apache.directory.server.core.partition.DefaultDirectoryPartitionNexus:722) DEBUG org.apache.directory.server.core.partition.DefaultDirectoryPartitionNexus - Check if DN 'ou=system' exists.
2006-04-19 12:46:09,123 101754 [SynchWorkerThread] (org.apache.directory.shared.ldap.name.DnParser:184) DEBUG org.apache.directory.shared.ldap.name.DnParser - Parsing DN 'ou=services,ou=configuration,ou=system'
2006-04-19 12:46:09,223 101854 [SynchWorkerThread] (org.apache.directory.shared.ldap.name.DnParser:184) DEBUG org.apache.directory.shared.ldap.name.DnParser - Parsing DN 'ou=system'
2006-04-19 12:46:09,304 101935 [SynchWorkerThread] (org.apache.directory.shared.ldap.name.DnParser:184) DEBUG org.apache.directory.shared.ldap.name.DnParser - Parsing DN 'ou=interceptors,ou=configuration,ou=system'
2006-04-19 12:46:09,424 102055 [SynchWorkerThread] (org.apache.directory.shared.ldap.name.DnParser:184) DEBUG org.apache.directory.shared.ldap.name.DnParser - Parsing DN 'ou=system'
2006-04-19 12:46:09,504 102135 [SynchWorkerThread] (org.apache.directory.shared.ldap.name.DnParser:184) DEBUG org.apache.directory.shared.ldap.name.DnParser - Parsing DN 'ou=configuration,ou=system'
2006-04-19 12:46:09,604 102235 [SynchWorkerThread] (org.apache.directory.shared.ldap.name.DnParser:184) DEBUG org.apache.directory.shared.ldap.name.DnParser - Parsing DN 'ou=system'
============================

This is a dump of the threads when I pause the debugger:

DestroyJavaVM@6d0, priority=5, in group 'main', status: 'RUNNING'

SynchWorkerThread@6ae, priority=5, in group 'main', status: 'WAIT'
wait():-1, Object.java
run():155, Service.java
run():534, Thread.java

SocketAcceptor-0@69f, priority=5, in group 'main', status: 'RUNNING'
poll0():-1, WindowsSelectorImpl.java
poll():263, WindowsSelectorImpl.java
access$400():245, WindowsSelectorImpl.java
doSelect():128, WindowsSelectorImpl.java
lockAndDoSelect():59, SelectorImpl.java
select():70, SelectorImpl.java
select():74, SelectorImpl.java
run():326, SocketAcceptorDelegate.java

Signal Dispatcher@e0 daemon, priority=10, in group 'system', status: 'RUNNING'

Finalizer@e1 daemon, priority=8, in group 'system', status: 'WAIT'
wait():-1, Object.java
remove():111, ReferenceQueue.java
remove():127, ReferenceQueue.java
run():159, Finalizer.java

Reference Handler@e2 daemon, priority=10, in group 'system', status: 'WAIT'
wait():-1, Object.java
wait():429, Object.java
run():115, Reference.java

The busy loop is in org.apache.mina.transport.socket.nio.support.SocketAcceptorDelegate.Worker.run() and appears to be because the line:

      int nKeys = selector.select();

never blocks after the resume, and hence the run() method becomes a busy loop. This may well be a bug in the JDK's nio package but a quick web search didn't turn up a match. At any rate it seems like a problem that will need to be worked around in MINA until the JDK is patched (if my diagnosis is correct) at it seems the selector is rendered inoperable by the close-lid/resume sequence.

I presume the same problem could be triggered on a desk-top machine with enough understanding about what WinXP does during a suspend, and why this upsets the NIO package.

Comments

[Trustin Lee]

This issue looks like a duplicate of DIRMINA-204

Please upgrade your JRE to 1.4.2_10 and let us know if it still is a problem.

[Norval Hope]

Confirmed problem went away after upgraded to JDK1.4.2_11