IV68216: DEADLOCK WHEN A FILEWRITER IS WORKED ON CONCURRENTLY BY MORE THA N ONE WRITER INSTANCES

APAR status

• Closed as program error.

Error description

• Error Message: Application hangs when two threads work on 2
  Writer instances with the same underlying FileWriter. An example
  scenario, one thread is working on a FileWriter while another
  thread is working on a PrintWriter instance which uses same
  FileWriter instance as the former thread.
  .
  Stack Trace: Blocked on: java/io/FileOutputStream@0x23144B88
  Owned by: "Thread-5"Java callstack:at
  java/io/OutputStreamWriter.write(OutputStreamWriter.java:212)at
  java/io/PrintWriter.write(PrintWriter.java:416)(entered lock:
  java/io/FileWriter@0x23144B60, entry count: 1)at
  testcase$bar.run(testcase.java:28)at
  java/lang/Thread.run(Thread.java:785)Blocked on:
  java/io/FileWriter@0x23144B60 Owned by: "Thread-6"Java
  callstack:at
  sun/nio/cs/StreamEncoder.write(StreamEncoder.java:129)at
  java/io/OutputStreamWriter.emptyBuffer(OutputStreamWriter.java:3
  02)(entered lock: java/io/FileOutputStream@0x23144B88, entry
  count: 2)at
  java/io/OutputStreamWriter.write(OutputStreamWriter.java:215)(en
  tered lock: java/io/FileOutputStream@0x23144B88, entry count:
  1)at testcase$bar.run(testcase.java:28)at
  java/lang/Thread.run(Thread.java:785)
  .
  

Local fix

Problem summary

• The hang arises due to threads acquiring multiple locks related
  to Writer class in different order.
  

Problem conclusion

• The locking sequences are streamlined to prevent the deadlocks
  in multi-threaded scenarios.
  .
  This APAR will be fixed in the following Java Releases:
     6    SR16 FP4  (6.0.16.4)
     8    SR1       (8.0.1.0)
     7 R1 SR3       (7.1.3.0)
     6 R1 SR8 FP4   (6.1.8.4)
     7    SR9       (7.0.9.0)
  .
  Contact your IBM Product's Service Team for these Service
  Refreshes and Fix Packs.
  For those running stand-alone, information about the available
  Service Refreshes and Fix Packs can be found at:
             https://www.ibm.com/developerworks/java/jdk/
  

Temporary fix

Comments

APAR Information

• APAR is sysrouted FROM one or more of the following:

• APAR is sysrouted TO one or more of the following:

Fix information

• Fixed component name

  JAVA CLASS LIBS

• Fixed component ID

  620700130

Applicable component levels

• R600 PSY

     UP

• R800 PSY

     UP

• R700 PSY

     UP