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100% CPU with ExtEventLoop #109
Description
See https://github.com/proxy/gist.github.com/kelunik/79f843c541aceb3927c5463cc643d502 for a reproduction script.
While the child process runs, php test.php consumes 100% CPU when running on the ExtEventLoop. Additionally, the connection is closed directly instead of one second later if there's currently a child process running.
See also https://twitter.com/kelunik/status/917757971790286848 and replies.
Activity
clue commentedon Oct 12, 2017
Thank you for filing this issue! I think it serves as a valid reference that suggests reactphp/child-process#51 may actually be an issue for some use cases.
Given that it's related to this known issue in another component, I don't see much that we could do here in this component.
I believe this has been answered, so I'm closing this for now. Please come back with more details if this problem persists and we can reopen this 👍
kelunik commentedon Oct 12, 2017
@clue It works fine with the
StreamSelectLoop. While it might be related to the linked issue, it probably shouldn't result in 100% CPU usage. The only expected issue with reactphp/child-process#51 is connections being kept open, butstream_socket_shutdownseems to solve that. Withoutstream_socket_shutdown, I get the expected hanging behavior with theStreamSelectLoop. I believe this is a separate issue.clue commentedon Oct 12, 2017
Can you send in a gist to reproduce this issue without the known issue linked above? Thank you.
kelunik commentedon Oct 12, 2017
Please re-open the issue, so I don't forget about it.
clue commentedon Oct 12, 2017
No worries, I'll make sure to ping you if nothing changes about this issue in a few days and will reopen if you send a gist to reproduce this! 👍 Thank you.
clue commentedon Oct 20, 2017
Ping @kelunik, I suppose this is still resolved? 👍
kelunik commentedon Oct 20, 2017
It's weird. If I try to look into it with
phpdbgand pause the execution and continue it again, the 100% CPU usage is gone. Seems to be a Heisenbug. Haven't found another reproduction case, because I'm not sure what causes it. So no, it's not resolved as stated previously. It's not the expected misbehavior that reactphp/child-process#51 might cause, as previously stated.clue commentedon Oct 20, 2017
@kelunik Thanks for trying to dig into this. If you happen to find a way to reproduce this, I'm happy to re-open this so we can look into this 👍
lajosbencz commentedon Jan 15, 2020
I've ran into this issue aswell, i'm installing
react/child-process:0.6.1from composer, and the default event loop (React\EventLoop\ExtUvLoop) consumes 100% of the CPU.If i explicitly set it to StreamSelectLoop, the process works as expected at around 5-10% CPU usage.
The project im using it in: https://github.com/lajosbencz/phrocman
Could it be purely related to the loop implementation, and nothing to do with the component itself?
clue commentedon Jan 15, 2020
@lajosbencz We're not aware of any such issues at the moment. Can you provide a minimal test script to reproduce this locally?
If this is related to spawning child-processes, can you take a look at one of the possible work-arounds for reactphp/child-process#51, such as clue/reactphp-sqlite#7?