Re: increasing the default WAL segment size

Hello,

On Mon, Mar 13, 2017 at 1:49 PM, Prabhat Sahu <prabhat(dot)sahu(at)enterprisedb(dot)com
> wrote:

> Hi,
>
> 2)Getting "Aborted (core dumped)" error at the time of running
> pg_basebackup , *(this issue is only coming on Linux32 ,not on Linux64)*
> we have double check to confirm it .
>
> Steps to reproduce on Linux32
>
>> ===================
>>> fetch the sources
>>> apply both the patches
>>> ./configure --with-zlib --enable-debug --enable-cassert
>>> --enable-depend --prefix=$PWD/edbpsql --with-openssl CFLAGS="-g -O0"; make
>>> all install
>>> Performed initdb with switch "--wal-segsize 4"
>>>
>>
>> Does the crash occur with only size 4?
>>
>
>
> Crash occurs for the value of *"--wal-segsize " 1, 2, 4, 8* with stack
> details as below :
>
> For value the value of *"--wal-segsize " 16, 32, 64*... (all multiple of
> 16) we are getting "Segmentation fault" message as below:
> [bin]$ ./pg_basebackup -v -D /tmp/slave16
> Segmentation fault (core dumped)
>
> and for all other values of* "--wal-segsize " 3, 5, 7, 9, 10, 11, ... 15,
> 17, 18,* ... we are getting invalid message during "initdb":
> [bin]$ ./initdb -D data1 --wal-segsize=17
> initdb: Invalid WAL segment size 17
>

The permissible values for the wal-segment size is power of 2 from 1 to
1024. Hence the Invalid message is expected behaviour.

Just to summarize, In Linux32, values 1 to 8 crashed and 16 to 1024 gave
segmentation fault.

>
>>
>>> start the server
>>> run pg_basebackup
>>>
>>> [centos(at)tushar-centos bin]$ ./pg_basebackup -v -D /tmp/myslave
>>> *** glibc detected *** ./pg_basebackup: free(): invalid pointer:
>>> 0x08da7f00 ***
>>>
>>> [centos(at)tushar-centos bin]$
>>>
>>> same scenario is working fine against HEAD (v10 ) on Linux32 [i.e no
>>> patch applied]
>>>
>>> [centos(at)tushar-centos bin]$ ./pg_basebackup --verbose -D /tmp/slave11
>>> pg_basebackup: initiating base backup, waiting for checkpoint to complete
>>> pg_basebackup: checkpoint completed
>>> pg_basebackup: transaction log start point: 0/2800024 on timeline 1
>>> pg_basebackup: starting background WAL receiver
>>> pg_basebackup: transaction log end point: 0/28000E4
>>> pg_basebackup: waiting for background process to finish streaming ...
>>> pg_basebackup: base backup completed
>>> [centos(at)tushar-centos bin]$
>>>
>>
>> Just to confirm, was this done with configure flag --with-wal-segsize=4 ?
>>
>
> we also have configure with the option "*--with-wal-segsize=4*" and
> getting warning.
> ./configure --with-zlib --enable-debug --enable-cassert
> --enable-depend --prefix=$PWD/inst --with-openssl CFLAGS="-g -O0"
> *--with-wal-segsize=4*
>
> configure: WARNING: unrecognized options: --with-wal-segsize
>

configure option was for the HEAD, without the patch applied.

I guess, I am missing something regarding the 32 bit machines, I am looking
into it.

Thank you,

--

Beena Emerson

EnterpriseDB: http://www.enterprisedb.com
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