Re: [Nagios-devel] Optimize status.cgi

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Hi Jonathan,

On 23 Dec 2009, at 02:26, Jonathan Kamens wrote:

> It adds the following optimizations to the code base:
> When iterating through the lines in the status.dat file, use a
> persistent buffer to read lines rather than freeing and reallocating
> a new buffer for every line. This reduces fragmentation of the
> malloc pool and reduces the amount of time spent in malloc() and
> free(). This is implemented by adding a new function,
> mmap_fgets_buf(), which is like mmap_fgets() except it takes an
> optional buffer to reuse if possible. I added this to both
> cgiutils.c and utils.c so that it can be used elsewhere in the code.
> When parsing the status.dat file, reduce the number of unnecessary
> calls to strcmp() by keeping track of when we know we're in a block
> and not checking for block-start sequences unnecessarily.
> Defer the sorting of the comment and scheduled downtime linked lists
> until they've all been read from status.dat. This makes a huge
> difference in performance -- it dwarfs by orders of magnitude the
> optimizations listed above. The way this is implemented is
> invisible to programs aside from status.cgi that call add_comment()
> or add_downtime(), but those programs can easily be modified to take
> advantage of the new functionality if they need to be sped up.
> I sincerely hope that the maintainers of Nagios will make an effort
> to include these changes in the next release. They represent a
> dramatic improvement in the performance and usability of the Web UI.

Just to let you know that (3) is now committed.

There's a test script which creates different numbers of comments/
downtimes and it shows that the code changes are indeed an order of
magnitude faster. Thanks again for the patch!

I've blogged about it here: http://opsview-blog.opsera.com/dotorg/2 ... -cgis.html

Ton


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Hi =
Jonathan,On 23 Dec 2009, at 02:26, Jonathan Kamens =
wrote: It adds the following optimizations to the code =
base: When iterating through the lines in the status.dat =
file, use a persistent buffer to read lines rather than freeing and =
reallocating a new buffer for every line.  This reduces =
fragmentation of the malloc pool and reduces the amount of time spent in =
malloc() and free().  This is implemented by adding a new function, =
mmap_fgets_buf(), which is like mmap_fgets() except it takes an optional =
buffer to reuse if possible.  I added this to both cgiutils.c and =
utils.c so that it can be used elsewhere in the code. When =
parsing the status.dat file, reduce the number of unnecessary calls to =
strcmp() by keeping track of when we know we're in a block and not =
checking for block-start sequences unnecessarily. Defer the =
sorting of the comment and scheduled downtime linked lists until they've =
all been read from status.dat.  This makes a huge =
difference in performance -- it dwarfs by orders of magnitude the =
optimizations listed above.  The way this is implemented is =
invisible to programs aside from status.cgi that call add_comment() or =
add_downtime(), but those programs can easily be modified to take =
advantage of the new functionality if they need to be sped up. =
I sincerely hope that the maintainers of Nagios will make an =
effort to include these changes in the next release.  They =
represent a dramatic improvement in the performance and usability of the =
Web UI.Just to let you know =
that (3) is now committed.There's a test =
script which creates different

...[email truncated]...


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