0005861: thread pool dead loop

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Category

Severity

Reproducibility

Date Submitted

Last Update

0005861

[Resin]

major

always

03-03-15 19:04

03-30-15 10:39

Reporter

cyflhn

View Status

public

Assigned To

ferg

Priority

normal

Resolution

no change required

Platform

Status

closed

Projection

none

OS Version

ETA

none

Fixed in Version

3.1.14

Product Version

3.1.13

Product Build

Summary

0005861: thread pool dead loop

Description

Thread pool dead loop often occurs especially when writing access log and the value of thread-max is not configured very high. I have checked the code. In ThreadPool.java, in method of schedule (line 481), if "poolItem"!=null and freeThreads >= freeCount, the "poolItem" will not be removed from link list headed by "_idleHead".But in line 547, method "start" of "poolItem" is invoked.So "poolItem" will become active. When "poolItem" becomes idle and returns to link list(line 702), if currently "_idleHead" points to "poolItem" itself, then _idleHead._next will point to itself. When the method "schedule" is invoked again, maybe the "poolItem" which is the current "_idleHead" is removed from link list and the poolItem._next is null(line 490). so "_idleHead" will be null forever if no other poolItems is returned to link list. Writing access log is invoked by startPriority(line 414). One thread which can not get a poolItem will block all other threads when writing access log. There is similar case in 0003509, but the problem still exists in 3.1.13.

Steps To Reproduce

Additional Information

Enviroment:
Linux/Sun JDK 1.7.55/Resin 3.1.13 Open source
Max Thread count: 256
about 10M visit one day
2cpu 4G memory

Attached Files

6988_1 [^] (26,233 bytes) 03-03-15 19:04

Relationships

Notes
(0006597) ferg 03-30-15 10:39	Resin 3.1 is frozen. Note, the max thread for a 64-bit system should be expanded to something much larger, like 4096, which will avoid the problem. The old default of 256 was small because at the time of Resin 3.1's release, 32 bit machines were more common and large numbers of threads were not well supported by the operating system.

Issue History
Date Modified	Username	Field	Change
03-03-15 19:04	cyflhn	New Issue
03-03-15 19:04	cyflhn	File Added: 6988_1
03-03-15 19:07	cyflhn	Issue Monitored: cyflhn
03-30-15 10:39	ferg	Note Added: 0006597
03-30-15 10:39	ferg	Assigned To	=> ferg
03-30-15 10:39	ferg	Status	new => closed
03-30-15 10:39	ferg	Resolution	open => no change required
03-30-15 10:39	ferg	Fixed in Version	=> 3.1.14

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