The Linux kernel's inability to gracefully handle low memory pressure

Re:The Linux kernel's inability to gracefully handle low mem... by kokey on Tuesday August 06, 2019 @04:00AM (#20623175)

The most common cause here is something causing a situation where some queries hang or takes a long time to complete, while also locking access to something, while new queries keep coming in. This builds up quickly.

A good way to catch this would be to have something log the list of running queries every couple of seconds. Look at this log after the crash and you'll hopefully be able to identify which are the long running processes, and which are the regular queries that builds up.

To fix it would be a combination of making the queries that cause the locking to be less like that, also perhaps putting in a limit on how many queries can build up and also implement a way for the regular queries that build up to time out or fail quicker or more gracefully.

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Re:The Linux kernel's inability to gracefully handle low mem... by HugThem on Tuesday August 06, 2019 @04:44AM (#20623408)

I fire the queries sequentially. So there is never more then one query running.

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Re:The Linux kernel's inability to gracefully handle low mem... by kilburn on Tuesday August 06, 2019 @07:14AM (#20624114)

The "once per day" part is suspicious. Maybe a scheduled backup is what's running the other query ;)

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Re:The Linux kernel's inability to gracefully handle low mem... by HugThem on Tuesday August 06, 2019 @07:22AM (#20624155)

I hade the same suspicion. Especially since the provider indeed runs a nightly backup of the VMs. But even after turning that off, the VM stalled the next night again.

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