[Catalyst] DProf

[Octavian Rasnita]

Thank you for describing those commands for me. They are helpful.

And sorry for my question that generated some off topic messages.

Octavian

----- Original Message ----- 
From: "Carl Johnstone" <catalyst at fadetoblack.me.uk>
To: "The elegant MVC web framework" <catalyst at lists.scsys.co.uk>
Sent: Monday, November 05, 2007 2:20 PM
Subject: Re: [Catalyst] DProf


>
> It's probably useful to tell you what these various commands are actually 
> doing, rather than just saying check-this and check-that...
>
> lsof = LiSt Open Files
>
> basically it lists every file that a process has open, that includes the 
> executable file itself and any libraries or shared code. The best way to 
> use it is with a process ID:
>
> lsof -p 1234
>
> Pick a process ID for one of the "stuck" httpd processes. It's use would 
> be looking to see if your app is reading files it shouldn't need to, or 
> maybe reading lots and lots of files.
>
>
>
> strace = System TRACE
>
> It'll allow you to attach to a process and show every system call the 
> program makes. System calls are things like 
> opening/reading/writing/closing files/network connections. Again you 
> should run it on one of your stuck processes that's using lots of CPU and 
> isn't finishing.
>
>
>
> Finally, you've found top, but I find that when you've got a server that's 
> overloaded, frequently "vmstat" provides more interesting information.
>
> vmstat 5
>
> Will give you a snapshot of what's happening on your system every 5 
> seconds. The columns are described on the man page, however it'll give you 
> a better breakdown of what's happening across the system as a whole 
> (although not what processes are causing that activity)
>
>
> Carl
>
>
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