Re: [PATCH] Identify LWLocks in tracepoints

Peter Eisentraut <peter.eisentraut@enterprisedb.com>

From: Peter Eisentraut <peter.eisentraut@enterprisedb.com>

To: Craig Ringer <craig.ringer@enterprisedb.com>

Cc: pgsql-hackers <pgsql-hackers@postgresql.org>

Date: 2021-04-14T13:20:59Z

Lists: pgsql-hackers

On 12.04.21 07:46, Craig Ringer wrote:
>      > To use systemtap semaphores (the _ENABLED macros) you need to run
>     dtrace
>      > -g to generate a probes.o then link that into postgres.
>      >
>      > I don't think we do that. I'll double check soon.
> 
>     We do that.  (It's -G.)
> 
> 
> Huh. I could've sworn we didn't. My mistake, it's there in 
> src/backend/Makefile .
> 
> In that case I'll amend the patch to use semaphore guards.

This whole thread is now obviously moved to consideration for PG15, but 
I did add an open item about this particular issue 
(https://wiki.postgresql.org/wiki/PostgreSQL_14_Open_Items, search for 
"dtrace").  So if you could produce a separate patch that adds the 
_ENABLED guards targeting PG14 (and PG13), that would be helpful.

Commits

Emit dummy statements for probes.d probes when disabled
- 0d204a4b09f7 13.3 landed
- fa8fbadb934b 14.0 landed
Prevent lwlock dtrace probes from unnecessary work
- e48ce7ef0ef8 13.3 landed
- b94409a02f61 14.0 landed
doc: Fix typo in logicaldecoding.sgml.
- 5fe83adad9ef 14.0 cited
Move lwlock-release probe back where it belongs
- 96ae658e6238 14.0 landed
Remove bogus tracepoint
- 09418bed67a7 14.0 landed
Simplify LWLock tranche machinery by removing array_base/array_stride.
- 3761fe3c20bb 10.0 cited
Improve LWLock scalability.
- ab5194e6f617 9.5.0 cited