0001588: Hessian SerializerFactory HashMaps involved in 100% CPU infinite loop? - Mantis

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ID

Category

Severity

Reproducibility

Date Submitted

Last Update

0001588

[Resin]

minor

sometimes

01-26-07 04:15

04-06-07 15:16

Reporter

bjornm

View Status

public

Assigned To

ferg

Priority

normal

Resolution

fixed

Platform

Status

closed

OS

Projection

none

OS Version

ETA

none

Fixed in Version

3.1.1

Product Version

3.0.20

Product Build

Summary

0001588: Hessian SerializerFactory HashMaps involved in 100% CPU infinite loop?

Description

During load tests to HessianServlets, we've sometimes experienced that the jvm would hang with 100% cpu. Thread dumps showed many threads were busy in HashMap.get:

"http-0.0.0.0-8080-8" daemon prio=1 tid=0x465bfbd8 nid=0x64e2 runnable [0x3f371000..0x3f3721b0]
        at java.util.HashMap.get(HashMap.java:346)
        at com.caucho.hessian.io.SerializerFactory.getSerializer(SerializerFactory.java)
        at com.caucho.hessian.io.HessianOutput.writeObject(HessianOutput.java:315)
        at com.caucho.hessian.io.JavaSerializer$FieldSerializer.serialize(JavaSerializer.java:242)
        at com.caucho.hessian.io.JavaSerializer.writeObject10(JavaSerializer.java:175)
        at com.caucho.hessian.io.JavaSerializer.writeObject(JavaSerializer.java:157)
        at com.caucho.hessian.io.HessianOutput.writeObject(HessianOutput.java:317)
        at com.caucho.hessian.server.HessianSkeleton.invoke(HessianSkeleton.java:172)
        at com.caucho.hessian.server.HessianServlet.service(HessianServlet.java:365)

A look at SerializerFactory shows it uses a set of hashmaps which are not synchronized:

  private HashMap _cachedSerializerMap;
  private HashMap _cachedDeserializerMap;
  private HashMap _cachedTypeDeserializerMap;

My guess is that if a HessianServlet receives many simultaneous calls during startup (when the maps are empty), concurrent read and write to the _cachedSerializerMap could cause this behavior. If this is the case, I suggest wrapping them in synchronizers:

_cachedDeserializerMap = Collections.synchronizedMap(new HashMap(8));

I have however been unable to reproduce this in some simple tests. Maybe someone who is more familiar with the code could advise.

Steps To Reproduce

Additional Information

About infinite loops in unsynchronized HashMaps:
http://blogs.opensymphony.com/plightbo/2005/07/hashmapget_can_cause_an_infini.html [^]

Relationships

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Issue History
Date Modified	Username	Field	Change
01-26-07 04:15	bjornm	New Issue
04-06-07 15:16	ferg	Assigned To	=> ferg
04-06-07 15:16	ferg	Status	new => closed
04-06-07 15:16	ferg	Resolution	open => fixed
04-06-07 15:16	ferg	Fixed in Version	=> 3.1.1

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