0002248: access to SessionManager#timeout is not synchronized

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Category

Severity

Reproducibility

Date Submitted

Last Update

0002248

[Resin]

minor

N/A

12-12-07 15:18

12-17-07 14:51

Reporter

aozarov

View Status

public

Assigned To

ferg

Priority

normal

Resolution

fixed

Status

closed

Product Version

2.1.x

Summary

0002248: access to SessionManager#timeout is not synchronized

Description

Both Crod and Alarm threads can call this method simultaneously.
The call to sessionList.clear() is outside of the synchronized block which can cause one thread to clear the list while the other one is processing it. I didn't check all the side-effects of this problem but can imagine that some sessions will not be cleaned/removed appropriately which may lead to some memory leaks.
Also, I am not sure if that can leave the ArrayList itself in an inconsistent state.

Additional Information

thread dump extract:

"resin-alarm" daemon prio=10 tid=0x00002aab502d2c00 nid=0x5180 waiting for monitor entry [0x000000004123a000..0x000000004123aba0]
   java.lang.Thread.State: BLOCKED (on object monitor)
    at com.caucho.http.session.SessionManager.timeout(SessionManager.java:1009)
    - waiting to lock <0x00002aaab683fbd0> (a com.caucho.util.LruCache)
    at com.caucho.server.http.Application.timeout(Application.java:3667)
    at com.caucho.server.http.VirtualHost.timeout(VirtualHost.java:1323)
    at com.caucho.server.http.ServletServer.timeout(ServletServer.java:1808)
    at com.caucho.server.http.ServletServer.handleAlarm(ServletServer.java:1758)
    at com.caucho.util.Alarm$AlarmThread.evaluateAlarm(Alarm.java:319)
    at com.caucho.util.Alarm$AlarmThread.run(Alarm.java:279)

"resin-cron" daemon prio=10 tid=0x00002aab4ec00000 nid=0x517f runnable [0x0000000041139000..0x0000000041139c20]
   java.lang.Thread.State: RUNNABLE
    at com.caucho.http.session.SessionManager.timeout(SessionManager.java:1017)
    - locked <0x00002aaab683fbd0> (a com.caucho.util.LruCache)
    at com.caucho.http.session.SessionManager.cron(SessionManager.java:1040)
    at com.caucho.server.http.Application.cron(Application.java:3701)
    at com.caucho.server.http.VirtualHost.cron(VirtualHost.java:1370)
    at com.caucho.server.http.ServletServer.cron(ServletServer.java:1950)
    at com.caucho.server.http.ServletServer.handleCron(ServletServer.java:1780)
    at com.caucho.util.Cron$CronThread.evaluateCron(Cron.java:199)
    at com.caucho.util.Cron$CronThread.run(Cron.java:163)

Attached Files

Relationships

Notes
(0002584) ferg 12-17-07 14:51	2.1.x is frozen and this issue does not apply to 3.0, since it uses a single alarm thread, i.e. that list is only single-threaded.

Issue History
Date Modified	Username	Field	Change
12-12-07 15:18	aozarov	New Issue
12-17-07 14:51	ferg	Note Added: 0002584
12-17-07 14:51	ferg	Assigned To	=> ferg
12-17-07 14:51	ferg	Status	new => closed
12-17-07 14:51	ferg	Resolution	open => fixed
12-17-07 14:51	ferg	Fixed in Version	=> 3.0.25

Mantis 1.0.0rc3[^]

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