03-03-2013
Unless you have replaced the standard UNIX sync command with something else, it will not start any database operations. The only thing the standard sync command does is schedule flushing of file system buffers to disk. On a large server with a huge amount of memory, flushing those buffers to disk may literally take an hour depending on the disk speeds and I/O data paths. While scheduled flushes are being processed, the system may indeed be sluggish.
Many database systems perform synchronous writes to be sure that data for completed transactions is safely stored on the underlying files rather than just sitting in buffers to be flushed later. It doesn't sound like your database software does this. If transactions are flushed when they are completed, there will be a small performance penalty at the end of each transaction (and you data would be safe if a power failure or other calamity occurs later), but you wouldn't suffer the big hits you're seeing now. Note that the sync command does not wait for data to be flushed before it returns; it just schedules the flush and returns letting the OS perform the flush to disk while it continues to process other requests.
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PPERL(1p) User Contributed Perl Documentation PPERL(1p)
NAME
PPerl - Make perl scripts persistent in memory
SYNOPSIS
$ pperl foo.pl
DESCRIPTION
This program turns ordinary perl scripts into long running daemons, making subsequent executions extremely fast. It forks several processes
for each script, allowing many processes to call the script at once.
It works a lot like SpeedyCGI, but is written a little differently. I didn't use the SpeedyCGI codebase, because I couldn't get it to
compile, and needed something ASAP.
The easiest way to use this is to change your shebang line from:
#!/usr/bin/perl -w
To use pperl instead:
#!/usr/bin/pperl -w
WARNINGS
Like other persistent environments, this one has problems with things like BEGIN blocks, global variables, etc. So beware, and try checking
the mod_perl guide at http://perl.apache.org/guide/ for lots of information that applies to many persistent perl environments.
Parameters
$ pperl <perl params> -- <pperl params> scriptname <script params>
The perl params are sent to the perl binary the first time it is started up. See perlrun for details.
The pperl params control how pperl works. Try -h for an overview.
The script params are passed to the script on every invocation. The script also gets any current environment variables, the current working
directory, and everything on STDIN.
Killing
In order to kill a currently running PPerl process, use:
pperl -- -k <scriptname>
You need to make sure the path to the script is the same as when it was invoked.
Alternatively look for a .pid file for the script in your tmp directory, and kill (with SIGINT) the process with that PID.
ENVIRONMENT
pperl uses the PPERL_TMP_PATH environment variable to determine the directory where to store the files used for inter-process
communication. By default, the subdirectory .pperl of the user's home directory is used.
BUGS
The process does not reload when the script or modules change.
$^S is not represented identically with respect to perl, since your script will be run within an eval block
AUTHOR
Matt Sergeant, matt@sergeant.org. Copyright 2001 MessageLabs Ltd.
SEE ALSO
perl. perlrun.
perl v5.14.2 2011-11-15 PPERL(1p)