On 19.01.2018 20:23, John Ferlan wrote:
RFC: https://www.redhat.com/archives/libvir-list/2018-January/msg00318.html
Adjustments since RFC...
Patches 1&2: No change, were already R-B'd Patch 3: Removed code as noted in code review, update commit message Patch 4: From old series removed, see below for more details Patch 9: no change NB: Patches 5-8 and 10 from Nikolay Shirokovskiy <nshirokovskiy@virtuozzo.com> are removed as they seemed to not be necessary
Replaced the former patch 4 with series of patches to (slowly) provide support to disable new connections, handle removing waiting jobs, causing the waiting workers to quit, and allow any running jobs to complete.
As it turns out, waiting for running jobs to complete cannot be done from the virNetServerClose callbacks because that means the event loop processing done during virNetServerRun will not allow any currently long running worker job thread a means to complete.
Hi, John. So you suggest a different appoarch. Instead of introducing means to help rpc threads to finish after event loop is finished (stateShutdown hook in my series) you suggest to block futher new rpc processing and then waiting running rpc calls to finish keeping event loop running for that purpose. This could lead to libvirtd never finish its termination if one of qemu processes do not respond for example. In case of long running operation such as migration finishing can take much time. On the over hand if we finish rpc threads abruptly as in case of stateShutdown hook we will deal with all possible error paths on daemon finishing. May be good approach is to abort long running operation, then give rpc threads some time to finish as you suggest and only after that finish them abruptly to handle hanging qemu etc. Also in this approach we keep event loop running for rpc threads only but there can be other threads that depend on the loop. For example if qemu is rebooted we spawn a thread that executes qemuProcessFakeReboot that sends commands to qemu (i.e. depends on event loop). We need to await such threads finishing too while keep event loop running. In approach of stateShutdown hook we finish all threads that uses qemu monitor by closing the monitor. And hack with timeout in a loop... I think of a different aproach for waiting rpc threads to finish their work. First let's make drain function only flush job queue and take some callback which will be called when all workers will be free from work (let's keep worker threads as Dan suggested). In this callback we can use same technique as in virNetDaemonSignalHandler. That is make some IO to set some flag in the event loop thread and cause virEventRunDefaultImpl to finish and then test this flag in virNetDaemonRun. Nikolay
So when virNetDaemonQuit is called as a result of the libvirtd signal handlers for SIG{QUIT|INT|TERM}, instead of just causing virNetServerRun to quit immediately, alter to using a quitRequested flag and then use that quitRequested flag to check for long running worker threads before causing the event loop to quit resulting in libvirtd being able to run through the virNetDaemonClose processing.
John Ferlan (9): libvirtd: Alter refcnt processing for domain server objects libvirtd: Alter refcnt processing for server program objects netserver: Remove ServiceToggle during ServerDispose util: Introduce virThreadPoolDrain rpc: Introduce virNetServerQuitRequested rpc: Introduce virNetServerWorkerCount rpc: Alter virNetDaemonQuit processing docs: Add news article for libvirtd issue APPLY ONLY FOR TESTING PURPOSES
daemon/libvirtd.c | 43 +++++++++++++++++++++++--------- docs/news.xml | 12 +++++++++ src/libvirt_private.syms | 1 + src/libvirt_remote.syms | 2 ++ src/qemu/qemu_driver.c | 5 ++++ src/rpc/virnetdaemon.c | 45 +++++++++++++++++++++++++++++++++- src/rpc/virnetserver.c | 52 ++++++++++++++++++++++++++++++++++++--- src/rpc/virnetserver.h | 4 +++ src/util/virthreadpool.c | 64 ++++++++++++++++++++++++++++++++++++++++-------- src/util/virthreadpool.h | 2 ++ 10 files changed, 204 insertions(+), 26 deletions(-)