Thread-safe Neo4j.start

[dwbutler]

As discussed in neo4jrb/activegraph#237, it seems Neo4j.start is not currently thread-safe. This fix solves the issue for me in both puma and torquebox-lite.

There were two problems:

• There was no lock around Neo4j::Core::Database#start, which allowed other threads concurrent access to this method. This fix introduces a lock around the whole method.
• @running was set to true in Neo4j::Core::Database before the database had actually completed start up. Since other threads check for db.running?, this caused these threads to access the database before it had actually completed initializing. This is now fixed by setting @running to true only after the database has finished initializing.

It turned out to be unnecessary to put a lock around Neo4j.start. In fact, doing so caused problems. (Please ignore the whitespace changes in neo4j.rb - I had trouble cleaning up my git history.)

[seenickcode]

Hello @dwbutler , it seems that this is still a problem at least with Heroku. Any insight into why? http://stackoverflow.com/questions/16246107/neo4j-doesnt-autostart-after-deploying-to-heroku

[dwbutler]

This is likely because the fixes I submitted have not made it into an official release yet. I'll go ahead and write a detailed explanation over on stack overflow.

[seenickcode]

thanks!

On Fri, Apr 26, 2013 at 7:15 PM, David Butler notifications@github.comwrote:

This is likely because the fixes I submitted have not made it into an
official release yet. I'll go ahead and write a detailed explanation over
on stack overflow.

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Reply to this email directly or view it on GitHubhttps://github.com//pull/23#issuecomment-17105111
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