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Katelyn Gadd
@antumbral
Turns out there is an OS-wide limit on how many threads you can have, and if you create an *operating system thread* for each host on your network (???) you will hit the limit
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Nick Craver
@Nick_Craver
Just found the AWS US-East-1 outage postmortem is up. Overall: increasing capacity causing more syncing overhead then slamming against configuration limits was the start of the cascading failure - an interesting read! Well worth a few minutes: aws.amazon.com/message/11201/
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Daniel Micay
@DanielMicay
Replying to
@t_murray
and
@antumbral
Linux vm.max_map_count also acts a per-process thread limit and is only 65530 by default even though it can be drastically higher. Stack overflow is generally detected via a guard region, and if you want to handle those errors you need to set up an alternate signal stack too.
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Daniel Micay
@DanielMicay
Replying to
@DanielMicay
@t_murray
and
@antumbral
Each thread requires up to 2 mappings or 4 mappings when supporting catching stack overflows. It can be higher for a hardened implementation. Since adjacent, identical mappings get merged, the count per thread will be lower until the address space gets fragmented over time.
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