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The following page has been changed by OwenOMalley: http://wiki.apache.org/lucene-hadoop/HowToDebugMapReducePrograms ------------------------------------------------------------------------------ There is also a configuration variable (keep.task.files.pattern) that will let you specify a task to keep by name, even if it doesn't fail. Other than that, logging is your friend. + == Other Java Debugging hints == + + To print information about the state of the threads in a Java program including: + * Call stack + * Locks held + * Deadlocks + Send a QUIT signal to the Java process: + {{{ + kill -QUIT <pid> + }}} + The output is sent to stdout. + + If that doesn't work because the output is being sent to /dev/null, you can also use the commands: + * '''jps''': List your java processes + * '''jstack''': Get the call stack for a given Java process + These commands were first included in Sun's Java 1.5. +
