| Lists: | pgsql-hackers |
|---|
| From: | Fujii Masao <masao(dot)fujii(at)gmail(dot)com> |
|---|---|
| To: | PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | elog during holding a spinlock is safe? |
| Date: | 2010-09-15 02:27:34 |
| Message-ID: | AANLkTim7ewtxN6orG+8z5mHByyeKx7zvBvpJpUvv1zw+@mail.gmail.com |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Lists: | pgsql-hackers |
Hi,
In HEAD, OwnLatch can elog during holding the spinlock WalSnd->mutex.
This seems to be unsafe because that elog would cause the walsender
to exit without releasing the spinlock. Because of the spinlock being
held, subsequent walsender would get stuck. I wonder if OwnLatch really
needs to be protected by the spinlock.
Regards,
--
Fujii Masao
NIPPON TELEGRAPH AND TELEPHONE CORPORATION
NTT Open Source Software Center
| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Fujii Masao <masao(dot)fujii(at)gmail(dot)com> |
| Cc: | PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>, Heikki Linnakangas <heikki(at)enterprisedb(dot)com> |
| Subject: | Re: elog during holding a spinlock is safe? |
| Date: | 2010-09-15 02:47:10 |
| Message-ID: | 24088.1284518830@sss.pgh.pa.us |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Lists: | pgsql-hackers |
Fujii Masao <masao(dot)fujii(at)gmail(dot)com> writes:
> In HEAD, OwnLatch can elog during holding the spinlock WalSnd->mutex.
> This seems to be unsafe
Even if it were safe, holding a spinlock through non-straight-line code
is a complete violation of the spinlock coding rules re the length of
time you're supposed to hold the lock. Heikki?
regards, tom lane
| From: | Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | Fujii Masao <masao(dot)fujii(at)gmail(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: elog during holding a spinlock is safe? |
| Date: | 2010-09-15 06:51:16 |
| Message-ID: | 4C906CE4.9010609@enterprisedb.com |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Lists: | pgsql-hackers |
On 15/09/10 05:47, Tom Lane wrote:
> Fujii Masao<masao(dot)fujii(at)gmail(dot)com> writes:
>> In HEAD, OwnLatch can elog during holding the spinlock WalSnd->mutex.
>> This seems to be unsafe
>
> Even if it were safe, holding a spinlock through non-straight-line code
> is a complete violation of the spinlock coding rules re the length of
> time you're supposed to hold the lock. Heikki?
Yep, that's an oversight. I'll move the OwnLatch call after the spinlock
is released.
--
Heikki Linnakangas
EnterpriseDB http://www.enterprisedb.com