[IO-802] Restore threadlocal for skipfully() byte buffer

• Type: Bug
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Assignee: Unassigned
• Reporter: Tim Allison
• Created: 13/Jun/23 13:42
• Updated: 13/Jun/23 22:21

Description

Over on TIKA-4065, we found that trying to upgrade to commons-io 2.12.0 or 2.13.0 caused one of our unit tests to fail. We found that dropping threadlocal on the buffer used in IOUtils.skipFully() in conjunction with Java's InflaterInputStream was the cause of the problem.

Our unit test shows that running skipFully() on a stream and then reading gets different results on the same underlying stream when running multithreaded. This is really bad. It appears to be confined to InflaterInputStream...so not a very common case.

On the commons-io's user list psteitz observed that Java's InflaterInputStream expects read access to the byte array passed in...so having multiple threads writing to the same static (not-thread local) byte array is dangerous. The behavior of Java's InflaterInputStream is surprising and not documented.

I have a demonstration of the problem here: https://github.com/tballison/commons-io/blob/TIKA-4065/src/test/java/org/apache/commons/io/IOUtilsMultithreadedTest.java

Issue Links

• causes: TIKA-4065 Apparent multithreading bug in HWP5 parser (2)