Thanks very much, Robert. Matt On Thu, Oct 17, 2019 at 5:24 PM Robert LeBlanc <robert@xxxxxxxxxxxxx> wrote: > > On Thu, Oct 17, 2019 at 2:03 PM Casey Bodley <cbodley@xxxxxxxxxx> wrote: > > > This is great news. Anything we can do to help in this effort as it is > > > very important for us? > > > > We would love help here. While most of the groundwork is done, so the > > remaining work is mostly mechanical. > > > > To summarize the strategy, the beast frontend spawns a coroutine for > > each client connection, and that coroutine is represented by a > > boost::asio::yield_context. We wrap this in an 'optional_yield' struct > > that gets passed to process_request(). The civetweb frontend always > > passes an empty object (ie null_yield) so that everything runs > > synchronously. When making calls into librados, we have a > > rgw_rados_operate() function that supports this optional_yield argument. > > If it gets a null_yield, it calls the blocking version of > > librados::IoCtx::operate(). Otherwise it calls a special > > librados::async_operate() function which suspends the coroutine until > > completion instead of blocking the thread. > > > > So most of the remaining work is in plumbing this optional_yield > > variable through all of the code paths under process_request() that call > > into librados. The rgw_rados_operate() helpers will log a "WARNING: > > blocking librados call" whenever they block inside of a beast frontend > > thread, so we can go through the rgw log to identify all of the places > > that still need a yield context. By iterating on this process, we can > > eventually remove all of the blocking calls, then set up regression > > testing to verify that no rgw logs contain that warning. > > > > Here's an example pr from Ali that adds the optional_yield to requests > > for bucket instance info: https://github.com/ceph/ceph/pull/27898. It > > extends the get_bucket_info() call to take optional_yield, and passes > > one in where available, using null_yield to mark the synchronous cases > > where one isn't available. > > I'll work to get familiar with the code base and see if I can submit > some PRs to help out. Things are a bit crazy, but this is very > important to us too. > > ---------------- > Robert LeBlanc > PGP Fingerprint 79A2 9CA4 6CC4 45DD A904 C70E E654 3BB2 FA62 B9F1 > _______________________________________________ > Dev mailing list -- dev@xxxxxxx > To unsubscribe send an email to dev-leave@xxxxxxx -- Matt Benjamin Red Hat, Inc. 315 West Huron Street, Suite 140A Ann Arbor, Michigan 48103 http://www.redhat.com/en/technologies/storage tel. 734-821-5101 fax. 734-769-8938 cel. 734-216-5309 _______________________________________________ Dev mailing list -- dev@xxxxxxx To unsubscribe send an email to dev-leave@xxxxxxx
