Re: Debugger freeze

As Dave mentioned, the interesting error message is probably this one:

could not find block containing chunk 0000000001176B70

That error occurs when the database server is trying to free a chunk of
memory from a MemoryContext, but can't find the chunk within the context
that owns the chunk.

There is no legitimate reason that this can happen (in other words, it's
a bug).

In you description you say:

Step a few times through the loop then take some time doing other
things in pgadmin iii

Do you think it's the delay that makes it fail? Or is it perhaps the
other activity (browsing other data, running queries)? What happens
if you let the debug session sit idle for a few minutes and then try
stepping through your code?

And (apologies if you've already answered these questions), can you run
the sample function (dbg_test()) without the debugger? Can you debug
other functions? Is this failure new with PG 9.5?

Thanks.

-- Korry

> The intriguing error message here is "could not find block containing
> chunk 0000000001176B70", which is coming from either the server or
> more likely, the debugger plugin.
>
> Korry - you're far more familiar with that code than me; any idea what
> could be causing this?
>
> On Sat, Feb 13, 2016 at 2:13 PM, Stefan Stefanov <stefanov(dot)sm(at)abv(dot)bg
> <mailto:stefanov(dot)sm(at)abv(dot)bg>> wrote:
>
> Hi Dave, this part of pg_log/postgresql-2016-02-13_000000.log
> might help.
>
> 2016-02-13 16:05:23 EET ERROR: select() failed waiting for target
> 2016-02-13 16:05:23 EET STATEMENT: SELECT
> p.func, p.targetName, p.linenumber,
> pldbg_get_source($1::INTEGER, p.func) AS src,
> (SELECT
> s.args
> FROM pldbg_get_stack($1::INTEGER) s
> WHERE s.func = p.func) AS args
> FROM pldbg_step_over($1::INTEGER) p
> 2016-02-13 16:05:26 EET WARNING: unrecognized message
>
> 2016-02-13 16:05:26 EET CONTEXT: PL/pgSQL function
> playground.dbg_test() line 8 at RAISE
> 2016-02-13 16:05:26 EET ERROR: could not find block containing
> chunk 0000000001176B70
> 2016-02-13 16:05:26 EET CONTEXT: PL/pgSQL function
> playground.dbg_test() line 8 at RAISE
> 2016-02-13 16:05:26 EET STATEMENT: SELECT * FROM
> playground.dbg_test()
> 2016-02-13 16:06:02 EET LOG: could not receive data from client:
> No connection could be made because the target machine actively
> refused it.
>
>
> 2016-02-13 16:06:02 EET LOG: could not receive data from client:
> No connection could be made because the target machine actively
> refused it.
>
>
> 2016-02-13 16:06:02 EET LOG: could not receive data from client:
> No connection could be made because the target machine actively
> refused it.
>
>
> 2016-02-13 16:06:02 EET ERROR: debugger connection(client side)
> terminated
> 2016-02-13 16:06:02 EET STATEMENT: SELECT * FROM
> pldbg_abort_target(1)
> 2016-02-13 16:06:02 EET LOG: could not send data to client: No
> connection could be made because the target machine actively
> refused it.
>
>
> 2016-02-13 16:06:02 EET STATEMENT: SELECT * FROM
> pldbg_abort_target(1)
> 2016-02-13 16:06:02 EET FATAL: connection to client lost
> 2016-02-13 16:06:02 EET LOG: could not receive data from client:
> No connection could be made because the target machine actively
> refused it.
>
>
>
> Sincerely, Stefan
>
>
>
> >-------- Оригинално писмо --------
> >От: Dave Page dpage(at)pgadmin(dot)org <mailto:dpage(at)pgadmin(dot)org>
> >Относно: Re: [pgadmin-support] Debugger freeze
> >До: Stefan Stefanov <stefanov(dot)sm(at)abv(dot)bg <mailto:stefanov(dot)sm(at)abv(dot)bg>>
> >Изпратено на: 12.02.2016 15:45
>
> Hi
>
> On Thu, Feb 11, 2016 at 6:36 PM, Stefan Stefanov
> <stefanov(dot)sm(at)abv(dot)bg> wrote:
>
> Dear Sir or Madam,
> I am writing to report a bug in pgadmin III 1.22.0 running on
> Windows 7 x64 connected to PostgreSQL 9.5.0 VC++ build 1800,
> 64 bit.
> To reproduce the bug create this trivial function using SQL
> query editor. The example is in "playground" schema.
>
> create function playground.dbg_test() returns void as
> $$
> declare
> i integer;
> t text;
> begin
> for i in 1 .. 100 loop
> t := 'XYZ' || to_char(i, '999');
> raise notice 'Round %', t;
> end loop;
> end;
> $$ language plpgsql;
>
> Right-click the function in Object browser then debug. Step a
> few times through the loop then take some time doing other
> things in pgadmin iii (browse data, run queries etc.) then
> return to the debug window and step again a few times. The
> debug window usually freezes (debug.png).
> Two locks remain (server status.png). The server may be
> cleared by cancelling the query of the global listener (pid
> 7748 in the example) but then pgadmin windows stop responding.
>
> This is preventing me from using the debugger and I need it
> badly.
>
>
> I've tried to reproduce this but am unable, even letting my
> machine go into powersave mode while the function is running.
>
> Can anyone else reproduce?
>
> Stefan, could it be that you're suffering from network
> disconnections? pgAdmin 3 really doesn't like them, and
> unfortunately it's a hard problem to fix given the current code
> structure (it's one of the things we're fixing in pgAdmin 4 which
> is completely new).
>
> --
> Dave Page
> Blog: http://pgsnake.blogspot.com
> Twitter: @pgsnake
>
> EnterpriseDB UK: http://www.enterprisedb.com
> The Enterprise PostgreSQL Company
>
>
>
>
> --
> Dave Page
> Blog: http://pgsnake.blogspot.com
> Twitter: @pgsnake
>
> EnterpriseDB UK: http://www.enterprisedb.com
> The Enterprise PostgreSQL Company