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 _______________________________________________ ceph-users mailing list -- ceph-users@xxxxxxx To unsubscribe send an email to ceph-users-leave@xxxxxxx
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