Thanks a lot ... we can just workaround this than in netty . Bye Norman > Am 19.12.2020 um 18:11 schrieb Jens Axboe <axboe@xxxxxxxxx>: > > On 12/19/20 9:29 AM, Jens Axboe wrote: >>> On 12/19/20 9:13 AM, Jens Axboe wrote: >>> On 12/18/20 7:49 PM, Josef wrote: >>>>> I'm happy to run _any_ reproducer, so please do let us know if you >>>>> manage to find something that I can run with netty. As long as it >>>>> includes instructions for exactly how to run it :-) >>>> >>>> cool :) I just created a repo for that: >>>> https://github.com/1Jo1/netty-io_uring-kernel-debugging.git >>>> >>>> - install jdk 1.8 >>>> - to run netty: ./mvnw compile exec:java >>>> -Dexec.mainClass="uring.netty.example.EchoUringServer" >>>> - to run the echo test: cargo run --release -- --address >>>> "127.0.0.1:2022" --number 200 --duration 20 --length 300 >>>> (https://github.com/haraldh/rust_echo_bench.git) >>>> - process kill -9 >>>> >>>> async flag is enabled and these operation are used: OP_READ, >>>> OP_WRITE, OP_POLL_ADD, OP_CLOSE, OP_ACCEPT >>>> >>>> (btw you can change the port in EchoUringServer.java) >>> >>> This is great! Not sure this is the same issue, but what I see here is >>> that we have leftover workers when the test is killed. This means the >>> rings aren't gone, and the memory isn't freed (and unaccounted), which >>> would ultimately lead to problems of course, similar to just an >>> accounting bug or race. >>> >>> The above _seems_ to be related to IOSQE_ASYNC. Trying to narrow it >>> down... >> >> Further narrowed down, it seems to be related to IOSQE_ASYNC on the >> read requests. I'm guessing there are cases where we end up not >> canceling them on ring close, hence the ring stays active, etc. >> >> If I just add a hack to clear IOSQE_ASYNC on IORING_OP_READ, then >> the test terminates fine on the kill -9. > > And even more so, it's IOSQE_ASYNC on the IORING_OP_READ on an eventfd > file descriptor. You probably don't want/mean to do that as it's > pollable, I guess it's done because you just set it on all reads for the > test? > > In any case, it should of course work. This is the leftover trace when > we should be exiting, but an io-wq worker is still trying to get data > from the eventfd: > > $ sudo cat /proc/2148/stack > [<0>] eventfd_read+0x160/0x260 > [<0>] io_iter_do_read+0x1b/0x40 > [<0>] io_read+0xa5/0x320 > [<0>] io_issue_sqe+0x23c/0xe80 > [<0>] io_wq_submit_work+0x6e/0x1a0 > [<0>] io_worker_handle_work+0x13d/0x4e0 > [<0>] io_wqe_worker+0x2aa/0x360 > [<0>] kthread+0x130/0x160 > [<0>] ret_from_fork+0x1f/0x30 > > which will never finish at this point, it should have been canceled. > > -- > Jens Axboe >
