Bug 317416

Description Edwin Kempin 2010-06-21 07:15:34 EDT

Build Identifier: 20100218-1602

jgit version: org.eclipse.jgit-0.8.4

In my scenario I'm using Gerrit for code review.
The problem is that the MsysGit Console gets stuck when I'm pushing a change to Gerrit:

Edwin@WDFD00185753A /c/temp/newProjects/project2 (master)
$ git push ssh://Edwin@localhost:29418/new/project2.git HEAD:refs/for/master
Counting objects: 3, done.
Writing objects: 100% (3/3), 216 bytes, done.
Total 3 (delta 0), reused 0 (delta 0)
_

By debugging the Gerrit Server I could identify the hanging thread:

Thread [SSH git-receive-pack '/new/project2.git' (Edwin)] (Suspended)	
	IndexPack.inflateFromInput(long) line: 998	
	IndexPack.whole(int, long, long) line: 824	
	IndexPack.indexOneObject() line: 783	
	IndexPack.index(ProgressMonitor) line: 394	
	ReceivePack.receivePack() line: 782	
	ReceivePack.service() line: 628	
	ReceivePack.receive(InputStream, OutputStream, OutputStream) line: 576	
	Receive.runImpl() line: 78	
	Receive(AbstractGitCommand).service() line: 104	
	AbstractGitCommand.access$0(AbstractGitCommand) line: 93	
	AbstractGitCommand$1.run() line: 69	
	BaseCommand$TaskThunk.run() line: 391	
	Executors$RunnableAdapter<T>.call() line: 441	
	FutureTask$Sync.innerRun() line: 303	
	ScheduledThreadPoolExecutor$ScheduledFutureTask<V>(FutureTask<V>).run() line: 138	
	ScheduledThreadPoolExecutor$ScheduledFutureTask<V>.access$301(ScheduledThreadPoolExecutor$ScheduledFutureTask) line: 98	
	ScheduledThreadPoolExecutor$ScheduledFutureTask<V>.run() line: 207	
	WorkQueue$ProjectTask<V>(WorkQueue$Task<V>).run() line: 324	
	ThreadPoolExecutor$Worker.runTask(Runnable) line: 886	
	ThreadPoolExecutor$Worker.run() line: 908	
	Thread.run() line: 679	

It hangs because there is an endless loop in org.eclipse.jgit.transport.IndexPack#inflateFromInput(...) method.
For me the while loop in inflateFromInput(...) is never finishing:

private byte[] inflateFromInput(final long sz) throws IOException {
  final byte[] dst = new byte[(int) sz];
  final Inflater inf = inflater;
  try {
    int n = 0;
    int p = -1;
    while (!inf.finished()) {
      if (inf.needsInput()) {
        if (p >= 0) {
          crc.update(buf, p, bAvail);
          use(bAvail);
        }
        p = fillFromInput(1);
        inf.setInput(buf, p, bAvail);
      }

      n += inf.inflate(dst, n, dst.length - n);
  }
  if (n != sz)
    throw new DataFormatException(JGitText.get().wrongDecompressedLength);
    n = bAvail - inf.getRemaining();
    if (n > 0) {
      crc.update(buf, p, n);
      use(n);
    }
    return dst;
  } catch (DataFormatException dfe) {
    throw corrupt(dfe);
  } finally {
    inf.reset();
  }
}

In my case the while loop is never finishing since inf.finished() always returns false. I guess this return value is correct since after the dst buffer is filled inf.getRemaining() still returns 22, so in principle there is something more to inflate. However for the call of Inflater#inflate(...) now always a length of 0 is given (dst.length - n = 0) and so the status of the inflater is never changed again. As a result I end up with an endless loop.

Here are some more values which I retrieved from the debugger, maybe they can help to solve the problem:
inf.finished()
	 (boolean) false	 
inf.getRemaining()
	 (int) 22
inf.getTotalIn()
	 (int) 12	 
inf.getBytesRead()
	 (long) 12
inf.getTotalOut()
	 (int) 6	 
inf.getBytesWritten()
	 (long) 6	 	 
inf.getAdler()
	 (int) 124256764
dst
	 (byte[]) [99, 46, 116, 120, 116, 10]
dst.length
	 (int) 6
n
	 (int) 6
this.dstIdx
	 (java.io.File) C:\workspaces\projects\test_site\git\new\project2.git\objects\incoming_6507350032416264131.idx
this.dstPack
	 (java.io.File) C:\workspaces\projects\test_site\git\new\project2.git\objects\incoming_6507350032416264131.pack
this.outputVersion
	 (int) 2
this.objectCount
	 (long) 3

Reproducible: Sometimes

Steps to Reproduce:
1. create new project in Gerrit:
ssh -p 29418 Edwin@localhost gerrit create-project --name new/project2
2. clone the Git repository:
git clone ssh://Edwin@localhost:29418/new/project2.git
3. create one dummy file in the empty Git repository and commit it
4. push the change to Gerrit
git push ssh://Edwin@localhost:29418/new/project2.git HEAD:refs/for/master
The push is hanging as explained in the details.

As described I've create one local Git repository from which I always can reproduce the problem by trying to push the latest commit. If it can help to solve the problem I can share this Git repository.
For other Git repositories which I created in the same way the problem is not occuring.