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Thread: how to debug into InitPostgres() and InitCatalogCache()?

how to debug into InitPostgres() and InitCatalogCache()?

From
土卜皿
Date:
hi, all
  I already can debug general postgres using "ddd" and "select pg_backend_pid();" ,  now, I want to study the details of the system catalog cache and system cache management, so I need to debug the function InitPostgres() and InitCatalogCache(), and I tried the following steps:

(1) in first terminal: 

ddd initdb

and set a breakpoint on the next executable line after “PG_CMD_OPEN” in function bootstrap_template1() ,

Then within gdb, use “r $myfolder/mydb”,

and found the cursor stop at the breakpoint

(2) in the second terminal:

ps aux | grep "bin\/postgres"

after get the posgtres server pid, start a new ddd without args, and within gdb, using "attach postgres.pid"

and set a breakpoint as InitCatalogCache()

(3) back to the first ddd window, hit the "cont" button. I hope it can stop at the second ddd's breakpoint, but nothing happened?

I must make mistake in some step, or my understanding is fully wrong, please give me some advice, thanks a lot!

Dillon

 


Re: how to debug into InitPostgres() and InitCatalogCache()?

From
土卜皿
Date:
2014-08-05 22:08 GMT+08:00 土卜皿 <pengcz.nwpu@gmail.com>:
hi, all
  I already can debug general postgres using "ddd" and "select pg_backend_pid();" ,  now, I want to study the details of the system catalog cache and system cache management, so I need to debug the function InitPostgres() and InitCatalogCache(), and I tried the following steps:

(1) in first terminal: 

ddd initdb

and set a breakpoint on the next executable line after “PG_CMD_OPEN” in function bootstrap_template1() ,

Then within gdb, use “r $myfolder/mydb”,

and found the cursor stop at the breakpoint

(2) in the second terminal:

ps aux | grep "bin\/postgres"

after get the posgtres server pid, start a new ddd without args, and within gdb, using "attach postgres.pid"

and set a breakpoint as InitCatalogCache()

(3) back to the first ddd window, hit the "cont" button. I hope it can stop at the second ddd's breakpoint, but nothing happened?

I must make mistake in some step, or my understanding is fully wrong, please give me some advice, thanks a lot


  I am sorry that this is a simple question.  I found that the above steps make the posgres reach     boot_yyparse() of BootstrapModeMain(void), which means postgres has already finished the initialization including InitCatalogCache(), and it was waiting query command or other user command .

  For debug initialization including system catalog cache, I add some code like:

 bool forDebug = true;

    while (forDebug){
      forDebug = true;
    }

in the InitPosgres()'s starting position.

 



Re: how to debug into InitPostgres() and InitCatalogCache()?

From
Alvaro Herrera
Date:
土卜皿 wrote:
> 2014-08-05 22:08 GMT+08:00 土卜皿 <pengcz.nwpu@gmail.com>:
> 
> > hi, all
> >   I already can debug general postgres using "ddd" and "select
> > pg_backend_pid();" ,  now, I want to study the details of the system
> > catalog cache and system cache management, so I need to debug the function
> > InitPostgres() and InitCatalogCache(), and I tried the following steps:

>   For debug initialization including system catalog cache, I add some code
> like:
> 
>  bool forDebug = true;
> 
>     while (forDebug){
>       forDebug = true;
>     }
> 
> in the InitPosgres()'s starting position.

There's also the -W switch, which makes it wait precisely to let you
attach a debugger.

-- 
Álvaro Herrera                http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services