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Using JavaSVN in Multithreaded Environment

When using JavaSVN in multithreaded applications one can have questions like these:

Q: Can I use one SVNRepository object in multiple threads? Is SVNRepository thread-safe?

A: No, you'd better not use one SVNRepository object in multiple threads. It may appear not thread safe. So, for every thread you have to instantiate a separate SVNRepository driver.

Another thing you should be aware about SVNRepository is that you can not call its methods from within those handlers that are provided to its methods (like those ISVNDirEntryHandler, ISVNReposrterBaton, etc.), since the repository access methods of SVNRepository are not reenterable, i.e. if an operation has been started, it must be already finished before invoking the next operation.

The same is for committing (getCommitEditor()): you must not make calls to your SVNRepository until you finish editing with calling an editor's closeEdit() method.

Q: Can I use one SVN*Client object in multiple threads? Are SVN*Client objects thread-safe?

A: The answer is still no. SVN*Client objects use different handlers for processing events/data (such as ISVNEventHandler, ISVNCommitHandler, etc.). For example, in one thread an SVN*Client object may be dispatching an event to the registered event handler in the same time as another thread tries to set a new event handler to that same SVN*Client object. What will be in result is unpredictable, it may cause your program to crash.

Another advice (well, it seems to be even more than advice:)) of using SVN*Client objects synchronously comes from the format of a Working Copy itself: during writing operations a Working Copy is locked for a period until the operation finishes. All other write access operations will be denied until the Working Copy is unlocked.

If you have any questions regarding JavaSVN, would like to report a bug or contribute a patch, please write to support@tmatesoft.com