|From:||Kyotaro HORIGUCHI <horiguchi(dot)kyotaro(at)lab(dot)ntt(dot)co(dot)jp>|
|Subject:||Let's remove DSM_INPL_NONE.|
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As in the other threads, we have had several good reasons
to remove DSM_IMPL_NONE in PG11. The attached patch doesn that.
It is amost a just-to-delete work but I see two issues raised so
1. That change can raise regression test failure on some
The reason is that initdb creates a database with
max_connection=10 from DSM failure caused by semaphore exhaustion
, even though regression test requires at least 20
connections. At that time it was "fixed" by setting
dynamic_shared_memory_type=none while detecting the number of
usable max_connections and shared buffers. Regardless of
whether the probing was succeeded or not, initdb finally creats a
database on that any DSM implementation is activated, since
initdb doesn't choose "none". Finally the test items for parallel
query actually suceeded.
For the reason above, I believe just increasing the minimum
fallback value of max_connections to 20 will work. Anyway it
is a problem to be fixed that initdb creates an inexecutable
database if it uses the fallback values of max_connections=10.
 Commit: d41ab71712a4457ed39d5471b23949872ac91def
2. Server may chooose unusable DSM implementation while initdb probing.
> Feel free to. Be just careful that the connection attempts in
> test_config_settings() should try to use the DSM implementation defined
> by choose_dsm_implementation().
Thank you for the advice. The probing fails with the default
setting if posix shared memory somehow fails on a platform like
Linux that is usually expected to have it. It's enough to choose
the implementation before probing. Some messages from initdb are
transposed as the result.
| creating directory /home/horiguti/data/data_ndsm ... ok
| creating subdirectories ... ok
| + selecting dynamic shared memory implementation ... posix
| selecting default max_connections ... 100
| selecting default shared_buffers ... 128MB
| - selecting dynamic shared memory implementation ... posix
Even though probing can end with failure in the case of , it
will not be a problem with the patch .
NTT Open Source Software Center
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