similar to: [PATCH nbdkit 0/2] connections: Protect open and close callbacks with the request lock.

I want to make my nbd forwarding plugin fully parallel - but to do that, I first need to make nbdkit itself fully parallel ;) With this series, I was finally able to demonstrate out-of-order responses when using qemu-io (which is great at sending back-to-back requests prior to waiting for responses) coupled with the nbd file plugin (which has a great feature of rdelay and wdelay, to make it

I've posted some of these patches or ideas before; but now I'm confident enough with the series that it should be ready to push; at any rate, I can now run test-socket-activation in a tight loop without triggering any crashes or hangs. With this in place, I'm going back to work on making the nbd forwarder wort with the parallel thread model. Eric Blake (8): sockets: Use

We noticed while writing various libnbd tests that when the delay filter is in use, there are scenarios where we had to resort to SIGKILL to get rid of nbdkit, because it was non-responsive to SIGINT. I'm still trying to figure out the best way to add testsuite coverage of this, but already proved to myself that it works from the command line, under two scenarios that both used to cause long

The previous incomplete patch was here: https://www.redhat.com/archives/libguestfs/2019-September/msg00049.html based on earlier discussion here: https://www.redhat.com/archives/libguestfs/2019-September/msg00047.html In v2: - The previous patch was incomplete. This version completes it by adding tests and extending nbdkit-sh-plugin. - nbdkit_export_name now returns NULL for error,

The concern is a client is blocked while processing a request. The nbdkit server design requires a thread per request being processed regardless of the number of connections or clients. We want to run 1000's of requests in parallel without needing a thread at nbdkit layer per request in flight. Our plugin layer is built around boost asio and a few threads in a worker pool running an io

These are a couple of patches in preparation for the Block Status implementation. While the patches (especially the second one) are very large they are really just elementary code motion. Rich.

Commit 9e6d990f exposed a pre-existing deadlock between the nbd plugin as client and parallel nbdkit as server. Prior to that commit, the deadlock was "resolved" because we unloaded the .so in parallel to a .close callback that never completed (yes, it's nasty that it usually? let the testsuite pass), but now we correctly refuse to unload a plugin that has not returned from .close,

This is a major rewrite compared to my v1 series, where I've tried a lot harder to ensure that we still accommodate building on Haiku (although I have not actually yet fired up a Haiku VM to try it for myself). I also managed to make the sh plugin fully parallel, on capable platforms. See also my question on patch 10 on whether I've picked the best naming convention. Eric Blake (17):

This is a cheap way to find some use-after-free and uninitialized read problems when using glibc. This in fact reveals a race during filter shutdown (which this commit does not fix): Thread 2 (Thread 0x7f1caaa5ffc0 (LWP 7223)): #0 0x00007f1cab0a05f8 in pthread_rwlock_wrlock () from /lib64/libpthread.so.0 #1 0x0000000000408842 in lock_unload () at locks.c:97 #2 0x00000000004066ff in

This fixes the long-standing crash on close when nbdkit exits. I did try first to fix threads so we're using a proper thread pool, but that's difficult to implement. So this does the minimal change needed to fix the crash instead. There are still two segfaults that happen during running the test suite. One is deliberately caused (tests/test-captive.sh). The other appears to be an

On 26.09.2016 14:29, Richard W.M. Jones wrote: > On Mon, Sep 26, 2016 at 02:18:02PM +0200, Carl-Daniel Hailfinger wrote: >> Hi, >> >> has anyone ever run "make check" from nbd against nbdkit with a python >> plugin? I usually get segfaults during such a run, and sometimes various >> other errors happen before the segfault, suggesting that some memory

First thing to say is that I need to do a *lot* more testing on this, so this is just an early peek. In particular, although it passed ‘make check && make check-valgrind’ I have *not* tested it against a multi-conn-aware client such as the Linux kernel >= 4.9. This implements NBD_FLAG_CAN_MULTI_CONN, described in the protocol doc as: "NBD_FLAG_CAN_MULTI_CONN: Indicates that

On Wed, Aug 05, 2020 at 03:40:43PM +0300, Nir Soffer wrote: > On Wed, Aug 5, 2020 at 2:58 PM Richard W.M. Jones <rjones@redhat.com> wrote: > > > > On Wed, Aug 05, 2020 at 02:39:44PM +0300, Nir Soffer wrote: > > > Can we use something like the file plugin? thread pool of workers, > > > each keeping open vddk handle, and serving requests in parallel from >

I believe this roughly implements Nir's proposal here: https://www.redhat.com/archives/libguestfs/2020-August/msg00028.html Unfortunately it doesn't work for me. It actually slows things down quite a lot, for reasons I don't understand. Note the adjustment of the pool-max parameter and how it affects the total time. The results are quite reproducible. $ ./nbdkit -r -U - vddk

Since the v1 series (0/4, at [1]), I've applied patches 1 and 2, rewritten patch 3 [Forbid NUL in export and context names] into patch 4 here, patch 4 there turned into patch 6 here, and everything else here is new. [1]https://www.redhat.com/archives/libguestfs/2019-September/msg00180.html I don't know if there is a handy reusable function for checking whether a string contains valid

Hi, has anyone ever run "make check" from nbd against nbdkit with a python plugin? I usually get segfaults during such a run, and sometimes various other errors happen before the segfault, suggesting that some memory corruption is underway. AFAICS a pure python plugin should not be able to cause memory corruption. Examples of nbdkit logs for running "make check" or subsets of

With this, I am finally able to get the nbd plugin to do out-of-order responses to the client. Once this series goes in, we should be ready for Rich to cut a release. Eric Blake (4): nbd: Split reading into separate thread nbd: Protect writes with mutex nbd: Enable parallel handling tests: Test parallel nbd behavior plugins/nbd/nbd.c | 217

This is the sort of thing I had in mind for option (1) here: https://www.redhat.com/archives/libguestfs/2019-September/msg00047.html It does reveal that the way we currently list exports is naive to say the least ... Rich.

ThreadSanitizer [1] pointed out that in the nbd plugin, nbd_close() can attempt close() in the main thread while the worker thread is still attempting to start a read(). Normally, if the read() loses the race, it will get a harmless EBADF that exits the worker thread (which is what we want, as we are closing the connection anyway); but if another connection happens to start in that window, we

Experimental and only very lightly tested so far. Rich.