java.io.IOException: Bad file descriptor
at java.io.RandomAccessFile.seek(Native Method)
at aoy.a(SourceFile:308)
at aoy.a(SourceFile:251)
at aoz.close(SourceFile:232)
at java.util.zip.DeflaterOutputStream.close(DeflaterOutputStream.java:143)
at java.io.FilterOutputStream.close(FilterOutputStream.java:143)
at apb.a(SourceFile:145)
at apb.c(SourceFile:133)
at ayi.b(SourceFile:30)
at ayi.run(SourceFile:23)
at java.lang.Thread.run(Thread.java:680)

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I see this error a LOT when messing around in SSP. It appears immediately after 'Saving chunks for level', about 15% of the times I run the program (121 out of 843). I've yet to notice any world or player data corruption. There's no rhyme or reason for when it happens vs not, and I can't reproduce it on demand. IIRC this also used to happen on 1.6.x (but I can't verify that at the moment). I've verified that my disk is OK via both DiskUtility and SMART.

Note: I'm using a custom java console log divert thing to see these. These errors are trapped from Minecraft's output stream, but Minecraft itself apparently does not write them into its own logs. Given this and that the error mentions zip, I'm guessing the problem lies somewhere with archiving and shuffling the logs around.