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Showing entries 1 to 10

Displaying posts with tag: debug (reset)

MySQL Stored Routines Debugger & Debugging API: sneak preview II, video
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This is the 2nd sneak preview of common_schema's rdebug: debugger & debugging API for MySQL stored routines (see 1st preview here).

rdebug will be released as part of common_schema, free and open sourced.

In this sneak preview I present:

  • Compiling multiple routines with debug info
  • Starting/stopping a debug session
  • Step-over, step-in, step-out
  • Showing stack trace
  • Showing the next-statement to execute
  • Viewing and manipulating local routine variables
  • Misc. meta routines

The quick technical overview

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MySQL Stored Routines Debugger & Debugging API: sneak preview video
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This is a sneak peek video introduction/preview of an in-development free and open source server side debugger & debugging API for MySQL stored routines.

MySQL does not provide server side debugging capabilities for stored routines. Some tools exist, including MySQL's own, that assist in stored routine debugging. These are all GUI based and, to the best of my knowledge, MS Windows based. There is one solution in alpha stage that is developed for Java/eclipse; I did not look at the code. See discussion here and here.

An ideal solution would be to have debugging API in the server itself - independently of your client, programming language or operating system. To the

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How to obtain all executing queries from a core file
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When investigating core files from crashes, one can quite easily figure out which query crashed, as we've seen.

Sometimes you want to just list all the currently executing statements, this is useful for diagnosing hangs or corruptions.

At least GDB 7 supports python macros, which can help us a lot here.   I use a core file from 5.5.27, also a non-debug build but not "stripped".   So it's a standard build made with -g allowing us to reference symbols.

I wrote a simplistic macro to iterate through

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Using the MySQL stack trace to isolate bugs
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I came across an interesting error reported on #mysql the other day. When I went through it with the reporter it looks like we uncovered up to two bugs in InnoDB (or rather XtraDB as it was Percona Server). I thought it might be useful to go through the error message, including the stack trace, to show that you don't need to be a developer to track down some useful information.

read more

How to produce a full stack trace for mysqld
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The information here was adapted from the AskMonty Knowledgebase.

There are two main parts to MariaDB and MySQL: The mysqld server and whatever client you use to interact with the server. The server is absolutely essential and must remain up and running. mysqld is normally very reliable, but there are rare occasions when it will fail. When mysqld fails hard (or core dump) it will, by default, write a stack trace in the 'hostname'.err file in the database directory. However, in some cases this is not enough to find out exactly what happened.

If you ever run into a situation where mysqld crashes and the 'hostname'.err file does not contain enough information for your DBA or support provider to diagnose the problem, you may need to use

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how to test the plain and encrypted SMTP/POP3/IMAP and HTTP protocols
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In this article I will describe how to test the plain and the encrypted SMTP/POP3/IMAP and HTTP protocols with telnet and the openssl s_client command.

list of references

For a complete list of available commands for the used protocols check the RFCs please:


sending mail

In the first example I will open a telnet

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pipe viewer – monitoring / limit the throughput of a pipe
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Pipe viewer is a command line tool which is used to monitor the throughput, display the estimated time of completion or to limit the transfer rate of a pipe (pipeline).

Install pipe viewer on Debian / Ubuntu with the following command.

apt-get install pv

On CentOS / Fedora / RedHat use the yum command to install pipe viewer

yum install pv

To use pipe viewer just insert the pv command between two processes to monitor the throughput of the pipe.

cat logfile.log.1 | pv | gzip -9 > logfile.log.1.gz
9,18MB 0:00:01 [ 9,1MB/s] [   <=>

Or limit the transfer rate of the pipe to a designated number of bytes.

cat logfile.log.1 | pv --rate-limit 100 | gzip -9 > logfile.log.1.gz
 300B 0:00:03 [ 101B/s ] [
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Dumping HTTP header with ngrep – the network grep
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To get the HTTP Header informations for specific clients connections use ngrep and a pattern or a regular expression that will match the packets.

install ngrep (example for debian / ubuntu):

apt-get install ngrep

These examples dumps HTTP header for any connection matching the string “images” on port 80.

user@host:~# ngrep -qi -W normal '/images/'  port 80
interface: lo (
match: /images/

T -> [AP]
GET /images/globe_blogs.gif HTTP/1.1..Host: frederikkonietzny.de..User-Agent: Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.6; de; rv: Gecko/20101026 Firefox/3
.6.12..Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8..Accept-Language: de-de,de;q=0.8,en-us;q=0.5,en;q=0.3..Accept-Encoding:
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Liveblogging at Confoo: [not just] PHP Performance by Rasmus Lerdorf
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Most of this stuff is not PHP specific, and Python or Ruby or Java or .NET developers can use the tools in this talk.

The session on joind.in, with user comments/feedback, is at http://joind.in/talk/view/1320.

Slides are at http://talks.php.net/show/confoo10

“My name is Rasmus, I’ve been around for a long time. I’ve been doing this web stuff since 1992/1993.”

“Generally performance is not a PHP problem.” Webservers not config’d, no expire headers on images, no favicon.

Tools: Firefox/Firebug extension called YSlow (developed by yahoo) gives you a grade on your site.

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Debugging AMP
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In a previous post, I mentioned the availability of the dtrace extension for Cool Stack's PHP.  Using this extension and the Cool Stack MySQL, it is possible to analyze the performance of your application running on this stack. At JavaOne, we demoed this using the open source MediaWiki and SugarCRM applications.  dtrace is especially useful in analyzing complex multi-tier applications like AMP. Thanks to Angelo Rajadurai for the creation of the scripts that I describe below.

Analyzing PHP calls

So, let's look at a simple dtrace script that counts how many times a particular PHP function is called :

#!/usr/sbin/dtrace -Zqs


You can copy

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Showing entries 1 to 10

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