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There are primarily three lists that are part of glusterd process, that are concurrently accessed. Namely, priv->volumes, priv->peers and volinfo->bricks_list. Big-lock approach ----------------- WHAT IS IT? Big lock is a coarse-grained lock which protects all three lists, mentioned above, from racy access. HOW DOES IT WORK? At any given point in time, glusterd's thread(s) are in execution _iff_ there is a preceding, inbound network event. Of course, the sigwaiter thread and timer thread are exceptions. A network event is an external trigger to glusterd, via the epoll thread, in the form of POLLIN and POLLERR. As long as we take the big-lock at all such entry points and yield it when we are done, we are guaranteed that all the network events, accessing the global lists, are serialised. This amounts to holding the big lock at - all the handlers of all the actors in glusterd. (POLLIN) - all the cbks in glusterd. (POLLIN) - rpc_notify (DISCONNECT event), if we access/modify one of the three lists. (POLLERR) In the case of synctask'ized volume operations, we must remember that, if we held the big lock for the entire duration of the handler, we may block other non-synctask rpc actors from executing. For eg, volume-start would block in PMAP SIGNIN, if done incorrectly. To prevent this, we need to yield the big lock, when we yield the synctask, and reacquire on waking up of the synctask. Change-Id: Ib929f9905b55fb6c3fc27fefb497a26dba058e4f BUG: 948686 Signed-off-by: Krishnan Parthasarathi <kparthas@redhat.com> Reviewed-on: http://review.gluster.org/4784 Reviewed-by: Jeff Darcy <jdarcy@redhat.com> Tested-by: Gluster Build System <jenkins@build.gluster.com> |
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| .. | ||
| basic | ||
| bugs | ||
| performance | ||
| utils | ||
| cluster.rc | ||
| dht.rc | ||
| fileio.rc | ||
| include.rc | ||
| README | ||
| volume.rc | ||
How to use test script framework. ================================= - Build and install the version of glusterfs with your changes. Make sure the installed version is accessible from $PATH. - To mount glusterfs, NEVER use 'mount -t glusterfs', instead use 'glusterfs -s ' method. This is because with the patch build setup doesnot install the /sbin/mount.glusterfs necessary, where as the glusterfs binary will be accessible with $PATH, and will pick the right version. - (optional) Set environment variables to specify location of export directories and mount points. Unless you have special requirements, the defaults should just work. The variables themselves can be found at the top of tests/include.rc. All of them can be overriden with environment variables. - Execute run-tests.sh in the top level directory as root. - If some test cases fail, you can execute the failed test case script directly bypassing run-tests.sh. At this time it might be useful to set the envrionment variable DEBUG=1 before running the individual test script directly by hand. - BE WARNED THAT THE TEST CASES DELETE /var/lib/glusterd/* !!!