Yaniv Kunda created EXEC-101:
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Summary: IOException when a process terminates before all buffered
input bytes have been written
Key: EXEC-101
URL: https://issues.apache.org/jira/browse/EXEC-101
Project: Commons Exec
Issue Type: Bug
Affects Versions: 1.3
Environment: Oracle JDK 1.8.0_72 x64 on MS Windows 10 Pro x64
Reporter: Yaniv Kunda
I encountered a serious glitch when using commons-exec 1.3 with Java 8 -
something that didn't happen with previous Java versions (tested with Java 5
and 7).
In order to feed a process' normal input stream, commons-exec uses
Process.getOutputStream() - which is normally a BufferedOutputStream, wrapping
a FileOutputStream, pointing to the OS's pseudo-file connected to the process'
normal input stream.
In Java 8, the process might terminate with the BufferedOutputStream still
having unwritten bytes in its buffer, while the underlying FileOutputStream
gets automatically closed.
DefaultExecutor always tries to close all of the process' streams, in
closeProcessStreams() - but because the process' BufferedOutputStream still has
bytes in its buffers (count > 0), it first tries to flush it to the underlying
FileOutputStreams, throwing an IOException (Stream closed).
The following scenario reproduces the problem:
# Use DefaultExecutor to start a process which does not expect (or read) any
bytes from the normal input stream.
# Feed the process (using PumpStreamHandler) a large amount of bytes.
# Execute
The change in behavior between Java 8 and previous versions actually lies
within FilterOutputStream, which contains the implementation of close() used by
BufferOutputStream - before Java 8, the implementation would ignore (swallow)
any exception cause by the call to flush() in close() - in Java 8, the
exception propagates.
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