[DERBY-5801] Sub-processes should write EMMA coverage data to separate files

• Type: Improvement
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 10.10.1.1
• Fix Version/s: 10.10.1.1
• Component/s: Test
• Assignee: Knut Anders Hatlen
• Reporter: Knut Anders Hatlen
• Created: 07/Jun/12 08:55
• Updated: 24/Jul/12 17:31
• Resolved: 07/Jun/12 15:17

Description

When generating EMMA coverage reports after running suites.All, I frequently see that coverage.ec is corrupted, and no report is produced. Typical failures look like this:

java.io.UTFDataFormatException: malformed input around byte 52
at java.io.DataInputStream.readUTF(DataInputStream.java:656)
at java.io.DataInputStream.readUTF(DataInputStream.java:564)
at com.vladium.emma.data.ClassDescriptor.readExternal(ClassDescriptor.java:171)
at com.vladium.emma.data.MetaData.readExternal(MetaData.java:228)
at com.vladium.emma.data.DataFactory.readEntry(DataFactory.java:770)
at com.vladium.emma.data.DataFactory.mergeload(DataFactory.java:461)
at com.vladium.emma.data.DataFactory.load(DataFactory.java:56)
at com.vladium.emma.report.ReportProcessor._run(ReportProcessor.java:175)
at com.vladium.emma.Processor.run(Processor.java:54)
at com.vladium.emma.report.reportCommand.run(reportCommand.java:130)
at emma.main(emma.java:40)

or

Exception in thread "main" com.vladium.emma.EMMARuntimeException: unexpected failure:
at com.vladium.emma.Command.exit(Command.java:237)
at com.vladium.emma.report.reportCommand.run(reportCommand.java:145)
at emma.main(emma.java:40)
Caused by: java.lang.OutOfMemoryError: Requested array size exceeds VM limit
at java.util.HashMap.<init>(HashMap.java:181)
at java.util.HashMap.<init>(HashMap.java:193)
at com.vladium.emma.data.MetaData.readExternal(MetaData.java:223)
at com.vladium.emma.data.DataFactory.readEntry(DataFactory.java:770)
at com.vladium.emma.data.DataFactory.mergeload(DataFactory.java:461)
at com.vladium.emma.data.DataFactory.load(DataFactory.java:56)
at com.vladium.emma.report.ReportProcessor._run(ReportProcessor.java:175)
at com.vladium.emma.Processor.run(Processor.java:54)
at com.vladium.emma.report.reportCommand.run(reportCommand.java:130)
... 1 more

I suspect that the problem is that all sub-processes spawned by the main test process write to the same file, sometimes multiple processes running at the same time, and that the file gets corrupted because there's no coordination between the processes when they're writing to it.

Experiments I have run also indicate that making the sub-processes write to different files helps (I haven't managed to reproduce the corruption yet with that change), so I suggest we make that change.