maria-discuss team mailing list archive

[Justin Swanhart <greenlion@xxxxxxxxx>]

oops, didn't copy the list.

---------- Forwarded message ----------
From: Justin Swanhart <greenlion@xxxxxxxxx>
Date: Wed, Feb 24, 2016 at 11:34 AM
Subject: Re: [Maria-discuss] New Question: Non-blocking calls from PHP
To: Federico Razzoli <federico_raz@xxxxxxxx>


Hi,

For now, if you want FIFO, just change the ORDER BY q_id DESC to ORDER BY
q_id.  The execution is parallel, it shouldn't starve queries.  I will
probably change this anyway by changing the structure of the `q` table to
have a primary key that sorts by the completion status and a unique key for
the auto_increment columns, then it can naturally be FIFO without causing
lock contention due to locking scanned rows in InnoDB.

The workaround for GET DIAGNOSTICS is to change it to not use that and just
put a generic error in the table.  You can't use conditional version syntax
in stored procs, and I don't want to have two different versions of the
script, since everyone really should be using 5.6+ or MariaDB 5.5+ IMHO.

I will remove count_running_threads, it isn't really needed because the
metadata locks held by the stored proc enforce that no more than
'thread_count' threads can run.  I will remove that code shortly.  I wasn't
using metadata locks when I started writing the tool.  This will remove the
dependency on global variables and the processlist.

It is version 1.0 and is still experimental :)  Thank you for the feedback.

--Justin

On Wed, Feb 24, 2016 at 10:58 AM, Federico Razzoli <federico_raz@xxxxxxxx>
wrote:

> Yes, GET DIAGNOSTICS is in 5.5 (and anyway, a workaround for older
> versions should be possible, correct?).
>
> Some comments:
>
> 1) The LIFO tables sounds to me a little dangerous. Of course
> "asynchronous" means "asynchronous", but under certain circumstances some
> queries could wait too much... don't you agree? Maybe the direction could
> depend from an option...
>
> 2) SELECT queries are "materialized", which is cool. But I don't
> understand how the user can associate an async query with the results table.
>
> 3) In MariaDB, the P_S is disabled by default, and a user can still
> disable it in MySQL. Also, in MariaDB global_status is in I_S, while MySQL
> has it in P_S (another funny incompatibility developed by Oracle). The
> first problem can probably be addressed with CONNECT (SRCDEF='show
> processlist') and the second with a view in async schema. Would you accept
> a patch?
>
> Probably more comments/questions will come. In the meanwhile, thanks for
> your work (again).
>
> bye
> Federico
>
>
> --------------------------------------------
> Mer 24/2/16, Justin Swanhart <greenlion@xxxxxxxxx> ha scritto:
>
>  Oggetto: Re: [Maria-discuss] New Question: Non-blocking calls from PHP
>  A: "Federico Razzoli" <federico_raz@xxxxxxxx>
>  Cc: "Maria Discuss" <maria-discuss@xxxxxxxxxxxxxxxxxxx>
>  Data: Mercoledì 24 febbraio 2016, 16:04
>
>  Hi,
>  It is
>  completely native.  It consists of a queue table, a thread
>  state table, a settings table, a stored procedure worker, an
>  event to execute the worker (more than one run in parallel)
>  and procs to drop off, check on, and get the results of a
>  SQL statement (which always waits if the SQL is not done
>  yet).
>  I don't know
>  if MariaDB 5.5 or 10 adds GET DIAGNOSTICS, but it will work
>  with any version that has it.  You can comment that out and
>  just put a generic error into the table if it isn't
>  supported, and it will work with any version that has
>  SIGNAL.
>  --Justin
>  On Wed, Feb 24, 2016 at
>  10:01 AM, Federico Razzoli <federico_raz@xxxxxxxx>
>  wrote:
>  Hi
>  Justin!
>
>  The name reminds me a a fatal trap for developers and sys
>  admins (async npm module), but the tools sounds useful.
>
>  Is it publicly available? Is it entirely implemented via
>  stored procedures + event scheduler?
>
>
>
>  bye
>
>  Federico
>
>
>
>
>
>  --------------------------------------------
>
>  Mer 24/2/16, Justin Swanhart <greenlion@xxxxxxxxx>
>  ha scritto:
>
>
>
>   Oggetto: Re: [Maria-discuss] New Question: Non-blocking
>  calls from PHP
>
>   A: "AskMonty KB" <noreply@xxxxxxxxxxxx>
>
>   Cc: "Maria Discuss" <maria-discuss@xxxxxxxxxxxxxxxxxxx>
>
>   Data: Mercoledì 24 febbraio 2016, 15:32
>
>
>
>   Replying
>
>   here in addition to the web page (ugh
>  Frankenstein's
>
>   monster)...
>
>
>
>   I just finished
>
>   the first version of 'async' which runs queries
>  in
>
>   the background (in parallel!) using a queue table, a
>  crafty
>
>   stored procedure for a worker thread, and an event
>  which
>
>   executes the workers.
>
>   http://swanhart.livejournal.com/138754.html
>
>
>
>   On Sun, Feb 21, 2016 at
>
>   8:55 AM, AskMonty KB <noreply@xxxxxxxxxxxx>
>
>   wrote:
>
>   Hello,
>
>
>
>
>
>
>
>   A new question has been asked in " MariaDB
>  Connector/C
>
>   API Functions" by shestero. Please answer it at
> http://mariadb.com/kb/en/non-blocking-calls-from-php/
>
>   as the person asking the question may not be subscribed
>  to
>
>   the mailing list.
>
>
>
>
>
>
>
>   --------------------------------
>
>
>
>   I want to use non-blocking API (
> https://mariadb.com/kb/en/mariadb/non-blocking-api-reference
>
>   ) from PHP.
>
>
>
>   Is it possible now?
>
>
>
>   If no, can anybody give me directions how to implement
>  my
>
>   own PHP-extension in C (using Connector/C) or update
>  the
>
>   existing module? I don't think it's very complex,
>  do
>
>   I need to add just wraper-like implementations using
>
>   blocking function as samples, don't I?
>
>
>
>   --------------------------------
>
>
>
>
>
>
>
>   To view or answer this question please visit:
> http://mariadb.com/kb/en/non-blocking-calls-from-php/
>
>
>
>
>
>
>
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>
>   -----Segue allegato-----
>
>
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