On 08.07.2016 16:48, Walter Klust wrote:
On 08.07.2016 16:38, Mark Phippard wrote:
On Fri, Jul 8, 2016 at 4:58 AM, Walter Klust <walter.kl...@elego.de> wrote:
Hello,
I have an interesting problem concerning JavaHL:
- Windows 7, JRE 8u66, Eclipse 4.2.1, Subclipse 1.8.22, JavaHL 1.8.10
- a changeset of around 2000 files; roughly 50% modified and 50% deleted
(probably to a large refactoring)
- on trying to commit the changes eclipse pops up a message after a short
time: "Internal error occured during SVNCommit", "bad C++ this"
I do not know if you are using changeset generically or referencing the
Eclipse changeset feature. But just to clarify for SVN devs, this is not
the SVN changelist feature. In terms of SVN commit, it would just be a
specific list of files to commit like any other commit. Eclipse changesets
are just a UI feature to organize the modified files.
I meant a list of files to commit. Thanks for the clarification.
- in the eclipse logs a stacktrace was found:
org.apache.subversion.javahl.JNIError: bad C++ this
at org.apache.subversion.javahl.SVNClient.dispose(Native Method)
at
org.tigris.subversion.svnclientadapter.javahl.AbstractJhlClientAdapter.dispose(AbstractJhlClientAdapter.java:3007)
at
org.tigris.subversion.subclipse.core.SVNClientManager.returnSVNClient(SVNClientManager.java:162)
at
org.tigris.subversion.subclipse.ui.operations.CommitOperation.execute(CommitOperation.java:113)
at
org.tigris.subversion.subclipse.ui.operations.SVNOperation.run(SVNOperation.java:90)
at
org.eclipse.team.internal.ui.actions.JobRunnableContext.run(JobRunnableContext.java:144)
at
org.eclipse.team.internal.ui.actions.JobRunnableContext$ResourceJob.runInWorkspace(JobRunnableContext.java:72)
at
org.eclipse.core.internal.resources.InternalWorkspaceJob.run(InternalWorkspaceJob.java:38)
at org.eclipse.core.internal.jobs.Worker.run(Worker.java:53)
- this error does not occur when trying to commit a subset of the changes,
e.g. any 2 of 4 subdirectories can be comitted successfully but not all 4
together.
It looks to me like a quantity problem; something like an internal buffer
overflow due to the large changeset. I tried to reproduce this with a
similar number of modified/deleted files but had no success so far.
Any ideas how to analyze this problem further ?
It sort of seems like it could be a Subclipse bug, though it is interesting
that it only manifests in specific scenarios. Makes me not really sure
where to look.
Does the commit work or record any errors? This exception is only
happening in some cleanup that occurs after the API calls would all be
completed or possibly after having processed an exception. IOW, this is
not failing during an API call, it is failing when Subclipse is just
disposing of the JavaHL client it obtained to make the API calls.
Something that is done for every API call.
The stack trace does not make a lot of sense either. This should be the
relevant place in the code:
org.tigris.subversion.subclipse.ui.operations.CommitOperation.execute(CommitOperation.java:113)
But that does not line up with anything that makes a lot of sense for the
error.
The commit does not work. Eclipse throws the message popup; the whole commit
process is then terminated.
By the way: when changing to svnkit this problem does not occur. Not sure what
this means about the root cause.
We analyzed the sources further:
The JNIError can happen if there are multiple parallel dispose calls. Now there is code which should prevent this in a
non thread safe environment:
-------
SVNClientManager.java
package org.tigris.subversion.subclipse.core;
...
public class SVNClientManager {
...
public void returnSVNClient(ISVNClientAdapter client) {
if (client == null || client.isThreadsafe())
return;
// For non-threadsafe clients we are done with the object so
// let it clean up any resources it has allocated.
client.dispose();
client = null;
}
-------
We think that this method is problematic with non-threadsafe clients. Assume
there are two threads calling this method:
- T1 enters, runs, executes client.dispose(). client is not null
- T2 enters, runs, passes the test because client is not null and also executes
client.dispose()
This would lead to the C++-Exception.
It should prevented in a non-threadsafe environment; the call
client.isThreadsafe() is not sufficient.
A fix for this would be to either declare the method returnSVNClient synchronized or to put the statements of the method
into a monitored block.
Thoughts ?
---
Walter Klust
