I've had a similar problem as well, but I've been using the single threaded async library - I actually find it simpler to use than the mt library.
The way I do it is this: During session connect - 1. Grab the file descriptor from the C library via zookeeper_interest() 2. If this is the first time I saw this file descriptor, and it's valid, do a setsockopt() on it to set SO_NOSIGPIPE to 1. When I need to "suspend" the session 1. close() the file descriptor 2. call zookeeper_close() on the handle zookeeper_close() will try to send the close session message at step 2 here. Normally, that would cause a SIGPIPE and your app would crash - but this time it won't because you've set SO_NOSIGPIPE on the socket. Instead, the Zookeeper library will see a regular error from its send operation and it'll free up the handle peacefully without closing the session. Best Regards, Martin Kou On Thu, May 10, 2012 at 4:11 PM, Jonathan Simms <[email protected]> wrote: > Michi, fair point, I actually just looked into it, there doesn't seem > to be a way through the api to re-establish the session. If you call > zookeeper_close on the handle: > > "After this call, the client session will no longer be valid. The > function will flush any outstanding send requests before return. As a > result it may block." > > I tried: > > * establish session with handle A > * copy clientid_t from handle A > * zookeeper_close handle A > * construct handle B using clientid_t values from handle A > > I get back a SESSION_EXPIRED from the server. (debug from mt lib here: > https://gist.github.com/3b7e4060746d03cef287) > > It would be *really* useful if i could basically "suspend" a session > while i forked, then reconnect and pick up where i left off. Is this > not possible? > > On Thu, May 10, 2012 at 6:41 PM, Michi Mutsuzaki <[email protected]> > wrote: > > Hi Jonathan, > > > > It would be very difficult to share multi-threaded zk handle with > > child process. I'm surprised it actually works on mac. I think saving > > session id/password and re-establishing the session in the child > > process is more robust and platform independent. > > > > Thanks! > > --Michi > > > > > > On Thu, May 10, 2012 at 12:45 PM, Jonathan Simms <[email protected]> > wrote: > >> Hi all, > >> > >> I'm the maintainer of the ruby zookeeper library, and I'm having > >> trouble getting consistent behavior when a user calls fork(). When > >> developing it on MacOS (using 3.3.5), I was able to fork, then > >> immediately call zookeeper_close() in the child, and then create a new > >> handle. Testing on Linux, the behavior is much more unpredictable. > >> Regularly, it seems there are segfaults when calling zookeeper_close. > >> https://gist.github.com/22338464cd47e0e50970 > >> > >> > >> So I guess my question is, is there any safe way to fork() while the > >> client is running? > >> > >> Another possibility i thought of is to note the session id/passwd, > >> close the client, fork, then re-open with the same id/passwd to > >> re-establish the session in the parent. > >> > >> Any recommendations? >
