Re: Problem in Multithreaded Environment

[Dan Diephouse]

Jukka Zitting wrote: Hi, On Jan 16, 2008 9:27 PM, Dan Diephouse <[EMAIL PROTECTED]> wrote: I have to lock the parent node before I can add child nodes? How does that help the situation? Then I have one thread that fails while the other succeeds. Lets say I have a node /spreadsheets and then I have two users using my web interface and they both add a spreadsheet to the repository at the same time. And spreadsheet nodes are represented by /spreadsheets/spreadsheet . Are you saying thats not possible? Jackrabbit handles such concurrent additions nicely as long as the added child nodes have separate names. See JCR-584 [1] for the details. Unfortunately this does not currently work with same name siblings. If I recall correctly there were some tricky semantic issues on how such cases should really be handled. Have you considered not using same name siblings in your content mode. See [2] and the related mailing list thread [3] for a rationale why locally (within a parent) unique node names are considered a better solution. Thanks. Follow up question: My data has no unique id or anything associated with it. So I'm going to have to generate an id then. I can do an increment type thing like this: public Node getNode(int nodeName, Node parent) {   try { return parent.addNode(new Integer(nodeName).toString()) }   catch (ItemExistsException e) { return getNode(nodeName+1); } } Lets say I have two open transactions where this is occurring at the same time. Will Tx#2 see that #1 has added a node named "1" and get an ItemExistsException even though I haven't committed Tx#1? Are there any bundled utilities within jackrabbit that can create unique ids across a cluster? Should I just use UUIDs? - Dan -- Dan Diephouse MuleSource http://mulesource.com | http://netzooid.com/blog