[Nagiosplug-devel] Perf Data
sghosh at sghosh.org
Tue Feb 18 17:42:13 UTC 2003
On Tue, 18 Feb 2003, Ethan Galstad wrote:
> There are two pipes of interest. One is the external command file,
> which is implemented as a FIFO and is restricted by the PIPE_BUF
> limit (512 bytes minimum for POSIX). Passive checks have to deal
> with this limit, but not active checks.
> The other pipe is used for IPC between the main (parent) Nagios
> process and the child processes. Each child writes the results of a
> plugin check (along with host/service name) to the pipe, at which
> point the parent reads it and process it. This pipe is also
> restricted by the PIPE_BUF limit. With host/service name overhead,
> you're left with about 350 bytes useable for plugin output+perfdata.
> It should be noted that *both* active and passive checks have results
> sent through this pipe. Passive checks enter through the FIFO and
> then get dumped into this pipe.
> If the size of the pipe becomes a real issue, we can probably break
> with POSIX compliance on most systems. The POSIX standard states a
> minimum of 512 bytes, but Linux has a 4K atomic write limit, while
> Solaris may have an 8K limit (I don't recall offhand). I guess I'll
> have to deal with it if and when it comes up.
The second pipe - is that a single pipe per running install from the
temp_file var in the config file?
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