Re: Using ProcSignal to get memory context stats from a running backend
| От | Craig Ringer |
|---|---|
| Тема | Re: Using ProcSignal to get memory context stats from a running backend |
| Дата | |
| Msg-id | CAMsr+YHUX1F8yCi=awoe=xHu918JRgyVf6gTcLnp1iQZuioFJg@mail.gmail.com обсуждение исходный текст |
| Ответ на | RE: Using ProcSignal to get memory context stats from a runningbackend ("Tsunakawa, Takayuki" <tsunakawa.takay@jp.fujitsu.com>) |
| Список | pgsql-hackers |
On 12 December 2017 at 12:25, Tsunakawa, Takayuki <tsunakawa.takay@jp.fujitsu.com> wrote:
From: Craig Ringer [mailto:craig@2ndquadrant.com]
> TL;DR: Lets add a ProcSignalReason that makes a backend call
> MemoryContextStats when it sees it and a C func that users can use to set
> it on a proc. Sane?
> So how about borrowing a ProcSignalReason entry for "dump a memory context
> summary at your earliest convenience" ? We could name it a more generic
> "dump debug data" in case we want to add things later.
>
> Then a new pg_log_debug_backend(int) function or something like that could
> signal the proc and let CHECK_FOR_INTERRUPTS handle calling
> MemoryContextStats next time it's called.
+1
That's one of things I wanted to do. It will be more useful on Windows. Would it work for autovac processes and background workers, etc. that connect to shared memory?
Anything that uses CHECK_FOR_INTERRUPTS() and is attached to PGXACT. So yeah, pretty much anything attached to shmem.
I have also wanted to dump stack traces. Linux (glibc) has backtrace_symbols(), and Windows has StackWalk()/StackWalk64(). Is it sane to make the function a hook?
In-proc stack traces are immensely useful, and IMO relatively safe in a proc that's already in a reasonable state. If your stack is mangled, making it worse with an in-proc stack trace is rarely your biggest concern. I'd LOVE to be able to do this.
However, I'd want to address anything like that quite separately to the change I proposed to expose an existing facility.
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