[HADOOP-2857] libhdfs: no way to set JVM args other than classpath

• Type: Improvement
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 0.16.0
• Fix Version/s: 0.18.0
• Hadoop Flags: Reviewed
• Assignee: Craig Macdonald
• Reporter: Craig Macdonald
• Created: 20/Feb/08 15:50
• Updated: 08/Jul/09 17:05
• Resolved: 29/Apr/08 21:28

Description

I would like a way to set other Java system properties and/or other Java VM arguments when using libhdfs - i.e. I want to be able to say start a profiler, attach a debugger, or increase the memory available to the VM.

At present, new JVMs are initialised from the getJNIEnv(void) method in src/c++/libhdfs/hdfsJniHelper.c
This method initialises the -Djava.class.path JVM argument from the CLASSPATH environment variable. I am proposing that another env variable should be added, the contents of which is passed (almost) verbatim as JVM arguments.

Eg, say the env var JVM_ARGS is used. The string from the env var would be tokenised on "one or more spaces", and would be passed as additional JVM arguments, by make a larger JavaVMOption options[] array, and setting vm_args.nOptions = 1+ number of passed arguments.

Only flaw I can see with this is that none of the passed parameters can contain spaces.