Related
I tried to import a large sql file through phpMyAdmin...But it kept showing error
'MySql server has gone away'
What to do?
As stated here:
Two most common reasons (and fixes) for the MySQL server has gone away
(error 2006) are:
Server timed out and closed the connection. How to fix:
check that wait_timeout variable in your mysqld’s my.cnf configuration file is large enough. On Debian: sudo nano
/etc/mysql/my.cnf, set wait_timeout = 600 seconds (you can
tweak/decrease this value when error 2006 is gone), then sudo
/etc/init.d/mysql restart. I didn't check, but the default value for
wait_timeout might be around 28800 seconds (8 hours).
Server dropped an incorrect or too large packet. If mysqld gets a packet that is too large or incorrect, it assumes that something has
gone wrong with the client and closes the connection. You can increase
the maximal packet size limit by increasing the value of
max_allowed_packet in my.cnf file. On Debian: sudo nano
/etc/mysql/my.cnf, set max_allowed_packet = 64M (you can
tweak/decrease this value when error 2006 is gone), then sudo
/etc/init.d/mysql restart.
Edit:
Notice that MySQL option files do not have their commands already available as comments (like in php.ini for instance). So you must type any change/tweak in my.cnf or my.ini and place them in mysql/data directory or in any of the other paths, under the proper group of options such as [client], [myslqd], etc. For example:
[mysqld]
wait_timeout = 600
max_allowed_packet = 64M
Then restart the server. To get their values, type in the mysql client:
> select ##wait_timeout;
> select ##max_allowed_packet;
For me this solution didn't work out so I executed
SET GLOBAL max_allowed_packet=1073741824;
in my SQL client.
If not able to change this with MYSql service running, you should stop the service and change the variable in "my.ini" file.
For example:
max_allowed_packet=20M
If you are working on XAMPP then you can fix the MySQL Server has gone away issue with following changes..
open your my.ini file
my.ini location is (D:\xampp\mysql\bin\my.ini)
change the following variable values
max_allowed_packet = 64M
innodb_lock_wait_timeout = 500
If you are running with default values then you have a lot of room to optimize your mysql configuration.
The first step I recommend is to increase the max_allowed_packet to 128M.
Then download the MySQL Tuning Primer script and run it. It will provide recommendations to several facets of your config for better performance.
Also look into adjusting your timeout values both in MySQL and PHP.
How big (file size) is the file you are importing and are you able to import the file using the mysql command line client instead of PHPMyAdmin?
If you are using MAMP on OS X, you will need to change the max_allowed_packet value in the template for MySQL.
You can find it at: File > Edit template > MySQL my.cnf
Then just search for max_allowed_packet, change the value and
save.
I had this error and other related ones, when I imported at 16 GB SQL file. For me, editing my.ini and setting the following (based on several different posts) in the [mysqld] section:
max_allowed_packet = 110M
innodb_buffer_pool_size=511M
innodb_log_file_size=500M
innodb_log_buffer_size = 800M
net_read_timeout = 600
net_write_timeout = 600
If you are running under Windows, go to the control panel, services, and look at the details for MySQL and you will see where my.ini is. Then after you edit and save my.ini, restart the mysql service (or restart the computer).
If you are using HeidiSQL, you can also set some or all of these using that.
I solved my issue with this short /etc/mysql/my.cnf file :
[mysqld]
wait_timeout = 600
max_allowed_packet = 100M
The other reason this can happen is running out of memory. Check /var/log/messages and make sure that your my.cnf is not set up to cause mysqld to allocate more memory than your machine has.
Your mysqld process can actually be killed by the kernel and then re-started by the "safe_mysqld" process without you realizing it.
Use top and watch the memory allocation while it's running to see what your headroom is.
make a backup of my.cnf before changing it.
I got same issue with
$image_base64 = base64_encode(file_get_contents($_FILES['file']['tmp_name']) );
$image = 'data:image/jpeg;base64,'.$image_base64;
$query = "insert into images(image) values('".$image."')";
mysqli_query($con,$query);
In \xampp\mysql\bin\my.ini file of phpmyadmin we get only
[mysqldump]
max_allowed_packet=110M
which is just for mysqldump -u root -p dbname . I resolved my issue by replacing above code with
max_allowed_packet=110M
[mysqldump]
max_allowed_packet=110M
I updated "max_allowed_packet" to 1024M, but it still wasn't working. It turns out my deployment script was running:
mysql --max_allowed_packet=512M --database=mydb -u root < .\db\db.sql
Be sure to explicitly specify a bigger number from the command line if you are donig it this way.
If your data includes BLOB data:
Note that an import of data from the command line seems to choke on BLOB data, resulting in the 'MySQL server has gone away' error.
To avoid this, re-create the mysqldump but with the --hex-blob flag:
http://dev.mysql.com/doc/refman/5.7/en/mysqldump.html#option_mysqldump_hex-blob
which will write out the data file with hex values rather than binary amongst other text.
PhpMyAdmin also has the option "Dump binary columns in hexadecimal notation (for example, "abc" becomes 0x616263)" which works nicely.
Note that there is a long-standing bug (as of December 2015) which means that GEOM columns are not converted:
Back up a table with a GEOMETRY column using mysqldump?
so using a program like PhpMyAdmin seems to be the only workaround (the option noted above does correctly convert GEOM columns).
If it takes a long time to fail, then enlarge the wait_timeout variable.
If it fails right away, enlarge the max_allowed_packet variable; it it still doesn't work, make sure the command is valid SQL. Mine had unescaped quotes which screwed everything up.
Also, if feasible, consider limiting the number of inserts of a single SQL command to, say, 1000. You can create a script that creates multiple statements out of a single one by reintroducing the INSERT... part every n inserts.
i got a similar error.. to solve this just open my.ini file..here at line no 36 change the value of maximum allowed packet size ie. max_allowed_packet = 20M
Make sure mysqld process does not restart because of service managers like systemd.
I had this problem in vagrant with centos 7. Configuration tweaks didn't help. Turned out it was systemd which killed mysqld service every time when it took too much memory.
I had similar error today when duplicating database (MySQL server has gone away...), but when I tried to restart mysql.server restart I got error
ERROR! The server quit without updating PID ...
This is how I solved it:
I opened up Applications/Utilities/ and ran Activity Monitor
quit mysqld
then was able to solve the error problem with
mysql.server restart
I am doing some large calculations which involves the mysql connection to stay long time and with heavy data. i was facing this "Mysql go away issue". So i tried t optimize the queries but that doen't helped me then i increased the mysql variables limit which is set to a lower value by default.
wait_timeout
max_allowed_packet
To the limit what ever suits to you it should be the Any Number * 1024(Bytes). you can login to terminal using 'mysql -u username - p' command and can check and change for these variable limits.
For GoDaddy shared hosting
On GoDaddy shared hosting accounts, it is tricky to tweak the PHP.ini etc files. However, there is another way and it just worked perfectly for me. (I just successfully uploaded a 3.8Mb .sql text file, containing 3100 rows and 145 cols. Using the IMPORT command in phpMyAdmin, I was getting the dreaded MySQL server has gone away error, and no further information.)
I found that Matt Butcher had the right answer. Like Matt, I had tried all kinds of tricks, from exporting MySQL databases in bite-sized chunks, to writing scripts that break large imports into smaller ones. But here is what worked:
(1) CPANEL ---> FILES (group) ---> BACKUP
(2a) Under "Partial Backups" heading...
(2b) Under "Download a MySQL Database Backup"
(2c) Choose your database and download a backup (this step optional, but wise)
(3a) Directly to the right of 2b, under heading "Restore a MySQL Database Backup"
(3b) Choose the .SQL import file from your local drive
(3c) True happiness will be yours (shortly....) Mine took about 5 seconds
I was able to use this method to import a single table. Nothing else in my database was affected -- but that is what step (2) above is intended to protect against.
Notes:
a. If you are unsure how to create a .SQL import file, use phpMyAdmin to export a table and modify that file structure.
SOURCE:
Matt Butcher 2010 Article
If increasing max_allowed_packet doesn't help.
I was getting the same error as you when importing a .sql file into my database via Sequel Pro.
The error still persisted after upping the max_allowed_packet to 512M so I ran the import in the command line instead with:
mysql --verbose -u root -p DatabaseName < MySQL.sql
It gave the following error:
ASCII '\0' appeared in the statement, but this is not allowed unless option --binary-mode is enabled
I found a couple helpful StackOverflow questions:
Enable binary mode while restoring a Database from an SQL dump
Mysql ERROR: ASCII '\0' while importing sql file on linux server
In my case, my .sql file was a little corrupt or something. The MySQL dump we get comes in two zip files that need to be concatenated together and then unzipped. I think the unzipping was interrupted initially, leaving the file with some odd characters and encodings. Getting a fresh MySQL dump and unzipping it properly worked for me.
Just wanted to add this here in case others find that increasing the max_allowed_packet variable was not helping.
None of the solutions regarding packet size or timeouts made any difference for me. I needed to disable ssl
mysql -u -p -hmyhost.com --disable-ssl db < file.sql
https://dev.mysql.com/doc/refman/5.7/en/encrypted-connections.html
I have a MySQL 5.1.61 database running behind two load balanced Apache webservers hosting a fairly busy (100K uniques per day) Wordpress sites. I'm caching with Cloudflare, W3TC, and Varnish. Most of the time, the database server handles traffic very well. "show full processlist" shows 20-40 queries at any given time, with most being in the sleep state.
Periodically, though (particularly when traffic spikes or when a large number of comments are cleared), MySQL stops responding. I'll find 1000-1500 queries running, many "sending data", etc. No particular query seems to be straining the database (they're all standard Wordpress queries), but it just seems like the simultaneous volume of requests causes all queries to hang up. I'm (usually) still able to log in, to run "show full processlist", or other queries, but the 1000+ queries already in there just sit. The only solution seems to be to restart mysql (sometimes violently via kill -9 if I can't connect).
All tables are innodb, server has 8 cores, 24GB RAM, plenty of disk space, and the following is my my.cnf:
[mysqld]
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
port=3306
skip-external-locking
skip-name-resolve
user=mysql
query_cache_type=1
query_cache_limit=16M
wait_timeout = 300
query_cache_size=128M
key_buffer_size=400M
thread_cache_size=50
table_cache=8192
skip-name-resolve
max_heap_table_size = 256M
tmp_table_size = 256M
innodb_file_per_table
innodb_buffer_pool_size = 5G
innodb_log_file_size=1G
#innodb_commit_concurrency = 32
#innodb_thread_concurrency = 32
innodb_flush_log_at_trx_commit = 0
thread_concurrency = 8
join_buffer_size = 256k
innodb_log_file_size = 256M
#innodb_concurrency_tickets = 220
thread_stack = 256K
max_allowed_packet=512M
max_connections=2500
# Default to using old password format for compatibility with mysql 3.x
# clients (those using the mysqlclient10 compatibility package).
old_passwords=1
#2012-11-03
#attempting a ram disk for tmp tables
tmpdir = /db/tmpfs01
[mysqld_safe]
log-error=/var/log/mysqld.log
pid-file=/var/run/mysqld/mysqld.pid
Any suggestions how I can potentially improve MySQL config, or other steps to maintain database stability under heavy load?
Like has been said, think outside the box and do sone rooting around why these queries are slow or somehow hung. An oldie but a good source of problems even for (supposedly;) intelligent system engineers is load balancing causing issues across webserver or database sessions. With all that caching and load balancing going on, are you sure everything is always connecting end-to-end as intended?
I agree with alditis & Bjoern
I'm pretty noobish with mysql but running mysqltuner can reveal some config optimisations based on recent queries of the DB https://github.com/rackerhacker/MySQLTuner-perl
And if possible store the DB files on a physically separate partition from the OS, the OS can consume IO which slows the DB. Like with Bjoern's logrotate issue.
First have a look at basic system behavior at the moment of problems. Use both vmstat and iostat if you can find any issues. See if the system starts swapping (pi,po columns in vmstat) and if lots of IO is happening. This is the first step in debugging your problem.
Another source of useful information is SHOW INNODB STATUS. See for http://www.mysqlperformanceblog.com/2006/07/17/show-innodb-status-walk-through/ on how to interpret the output.
It might be that at a certain point in time your writes are killing read performance because they flush the query cache.
I tried to import a large sql file through phpMyAdmin...But it kept showing error
'MySql server has gone away'
What to do?
As stated here:
Two most common reasons (and fixes) for the MySQL server has gone away
(error 2006) are:
Server timed out and closed the connection. How to fix:
check that wait_timeout variable in your mysqld’s my.cnf configuration file is large enough. On Debian: sudo nano
/etc/mysql/my.cnf, set wait_timeout = 600 seconds (you can
tweak/decrease this value when error 2006 is gone), then sudo
/etc/init.d/mysql restart. I didn't check, but the default value for
wait_timeout might be around 28800 seconds (8 hours).
Server dropped an incorrect or too large packet. If mysqld gets a packet that is too large or incorrect, it assumes that something has
gone wrong with the client and closes the connection. You can increase
the maximal packet size limit by increasing the value of
max_allowed_packet in my.cnf file. On Debian: sudo nano
/etc/mysql/my.cnf, set max_allowed_packet = 64M (you can
tweak/decrease this value when error 2006 is gone), then sudo
/etc/init.d/mysql restart.
Edit:
Notice that MySQL option files do not have their commands already available as comments (like in php.ini for instance). So you must type any change/tweak in my.cnf or my.ini and place them in mysql/data directory or in any of the other paths, under the proper group of options such as [client], [myslqd], etc. For example:
[mysqld]
wait_timeout = 600
max_allowed_packet = 64M
Then restart the server. To get their values, type in the mysql client:
> select ##wait_timeout;
> select ##max_allowed_packet;
For me this solution didn't work out so I executed
SET GLOBAL max_allowed_packet=1073741824;
in my SQL client.
If not able to change this with MYSql service running, you should stop the service and change the variable in "my.ini" file.
For example:
max_allowed_packet=20M
If you are working on XAMPP then you can fix the MySQL Server has gone away issue with following changes..
open your my.ini file
my.ini location is (D:\xampp\mysql\bin\my.ini)
change the following variable values
max_allowed_packet = 64M
innodb_lock_wait_timeout = 500
If you are running with default values then you have a lot of room to optimize your mysql configuration.
The first step I recommend is to increase the max_allowed_packet to 128M.
Then download the MySQL Tuning Primer script and run it. It will provide recommendations to several facets of your config for better performance.
Also look into adjusting your timeout values both in MySQL and PHP.
How big (file size) is the file you are importing and are you able to import the file using the mysql command line client instead of PHPMyAdmin?
If you are using MAMP on OS X, you will need to change the max_allowed_packet value in the template for MySQL.
You can find it at: File > Edit template > MySQL my.cnf
Then just search for max_allowed_packet, change the value and
save.
I had this error and other related ones, when I imported at 16 GB SQL file. For me, editing my.ini and setting the following (based on several different posts) in the [mysqld] section:
max_allowed_packet = 110M
innodb_buffer_pool_size=511M
innodb_log_file_size=500M
innodb_log_buffer_size = 800M
net_read_timeout = 600
net_write_timeout = 600
If you are running under Windows, go to the control panel, services, and look at the details for MySQL and you will see where my.ini is. Then after you edit and save my.ini, restart the mysql service (or restart the computer).
If you are using HeidiSQL, you can also set some or all of these using that.
I solved my issue with this short /etc/mysql/my.cnf file :
[mysqld]
wait_timeout = 600
max_allowed_packet = 100M
The other reason this can happen is running out of memory. Check /var/log/messages and make sure that your my.cnf is not set up to cause mysqld to allocate more memory than your machine has.
Your mysqld process can actually be killed by the kernel and then re-started by the "safe_mysqld" process without you realizing it.
Use top and watch the memory allocation while it's running to see what your headroom is.
make a backup of my.cnf before changing it.
I got same issue with
$image_base64 = base64_encode(file_get_contents($_FILES['file']['tmp_name']) );
$image = 'data:image/jpeg;base64,'.$image_base64;
$query = "insert into images(image) values('".$image."')";
mysqli_query($con,$query);
In \xampp\mysql\bin\my.ini file of phpmyadmin we get only
[mysqldump]
max_allowed_packet=110M
which is just for mysqldump -u root -p dbname . I resolved my issue by replacing above code with
max_allowed_packet=110M
[mysqldump]
max_allowed_packet=110M
I updated "max_allowed_packet" to 1024M, but it still wasn't working. It turns out my deployment script was running:
mysql --max_allowed_packet=512M --database=mydb -u root < .\db\db.sql
Be sure to explicitly specify a bigger number from the command line if you are donig it this way.
If your data includes BLOB data:
Note that an import of data from the command line seems to choke on BLOB data, resulting in the 'MySQL server has gone away' error.
To avoid this, re-create the mysqldump but with the --hex-blob flag:
http://dev.mysql.com/doc/refman/5.7/en/mysqldump.html#option_mysqldump_hex-blob
which will write out the data file with hex values rather than binary amongst other text.
PhpMyAdmin also has the option "Dump binary columns in hexadecimal notation (for example, "abc" becomes 0x616263)" which works nicely.
Note that there is a long-standing bug (as of December 2015) which means that GEOM columns are not converted:
Back up a table with a GEOMETRY column using mysqldump?
so using a program like PhpMyAdmin seems to be the only workaround (the option noted above does correctly convert GEOM columns).
If it takes a long time to fail, then enlarge the wait_timeout variable.
If it fails right away, enlarge the max_allowed_packet variable; it it still doesn't work, make sure the command is valid SQL. Mine had unescaped quotes which screwed everything up.
Also, if feasible, consider limiting the number of inserts of a single SQL command to, say, 1000. You can create a script that creates multiple statements out of a single one by reintroducing the INSERT... part every n inserts.
i got a similar error.. to solve this just open my.ini file..here at line no 36 change the value of maximum allowed packet size ie. max_allowed_packet = 20M
Make sure mysqld process does not restart because of service managers like systemd.
I had this problem in vagrant with centos 7. Configuration tweaks didn't help. Turned out it was systemd which killed mysqld service every time when it took too much memory.
I had similar error today when duplicating database (MySQL server has gone away...), but when I tried to restart mysql.server restart I got error
ERROR! The server quit without updating PID ...
This is how I solved it:
I opened up Applications/Utilities/ and ran Activity Monitor
quit mysqld
then was able to solve the error problem with
mysql.server restart
I am doing some large calculations which involves the mysql connection to stay long time and with heavy data. i was facing this "Mysql go away issue". So i tried t optimize the queries but that doen't helped me then i increased the mysql variables limit which is set to a lower value by default.
wait_timeout
max_allowed_packet
To the limit what ever suits to you it should be the Any Number * 1024(Bytes). you can login to terminal using 'mysql -u username - p' command and can check and change for these variable limits.
For GoDaddy shared hosting
On GoDaddy shared hosting accounts, it is tricky to tweak the PHP.ini etc files. However, there is another way and it just worked perfectly for me. (I just successfully uploaded a 3.8Mb .sql text file, containing 3100 rows and 145 cols. Using the IMPORT command in phpMyAdmin, I was getting the dreaded MySQL server has gone away error, and no further information.)
I found that Matt Butcher had the right answer. Like Matt, I had tried all kinds of tricks, from exporting MySQL databases in bite-sized chunks, to writing scripts that break large imports into smaller ones. But here is what worked:
(1) CPANEL ---> FILES (group) ---> BACKUP
(2a) Under "Partial Backups" heading...
(2b) Under "Download a MySQL Database Backup"
(2c) Choose your database and download a backup (this step optional, but wise)
(3a) Directly to the right of 2b, under heading "Restore a MySQL Database Backup"
(3b) Choose the .SQL import file from your local drive
(3c) True happiness will be yours (shortly....) Mine took about 5 seconds
I was able to use this method to import a single table. Nothing else in my database was affected -- but that is what step (2) above is intended to protect against.
Notes:
a. If you are unsure how to create a .SQL import file, use phpMyAdmin to export a table and modify that file structure.
SOURCE:
Matt Butcher 2010 Article
If increasing max_allowed_packet doesn't help.
I was getting the same error as you when importing a .sql file into my database via Sequel Pro.
The error still persisted after upping the max_allowed_packet to 512M so I ran the import in the command line instead with:
mysql --verbose -u root -p DatabaseName < MySQL.sql
It gave the following error:
ASCII '\0' appeared in the statement, but this is not allowed unless option --binary-mode is enabled
I found a couple helpful StackOverflow questions:
Enable binary mode while restoring a Database from an SQL dump
Mysql ERROR: ASCII '\0' while importing sql file on linux server
In my case, my .sql file was a little corrupt or something. The MySQL dump we get comes in two zip files that need to be concatenated together and then unzipped. I think the unzipping was interrupted initially, leaving the file with some odd characters and encodings. Getting a fresh MySQL dump and unzipping it properly worked for me.
Just wanted to add this here in case others find that increasing the max_allowed_packet variable was not helping.
None of the solutions regarding packet size or timeouts made any difference for me. I needed to disable ssl
mysql -u -p -hmyhost.com --disable-ssl db < file.sql
https://dev.mysql.com/doc/refman/5.7/en/encrypted-connections.html
I have LAMP server having 4 core CPU and 32 GB RAM.We are running a large website on it. I have following issues now in my server.
When I use Mysqlreport tool to monitor the mysql server i am always seeing the connection usage as below. And the users reporting connection issues in the website.
_
Connections _______________________________
Max used 251 of 250 %Max: 100.40 Total 748.71k 3.5/s
But when I use "show process list" command it will output nothing. We are using MyISAM engine for all our DBs.
My Mysql Config File is pasted below:
######################
[mysqld]
max_connections = 250
set-variable=local-infile=0
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
user=mysql
skip-name-resolve
skip-bdb
wait_timeout = 60
thread_cache_size = 100
table_cache = 1024
key_buffer = 384M
log_slow_queries=/mysql-log/mysql-slow.log
query-cache-size=512M
query-cache-type=1
query_cache_limit=20M
[mysqld_safe]
log-error=/var/log/mysqld.log
pid-file=/var/run/mysqld/mysqld.pid
#
Who is using my Mysql connection pool? How can I find it?
And i have another issue.
Sometimes the Load average goes beyond 4-8 range. See below:
13:40:02 up 2 days, 10:39, 0 users, load average: 5.03, 1.68, 0.93
At that time i can see mysql is the top consumer of the CPU. Is there any optimization needed in mysql Server?
Please reply to my above two queries.
Thanks in advance,
Aruns
I noticed that you are already using MySQL Query Cache.
Have you tried using MySQL workbench to connect to your MySQL database? It offers a graphical way of checking out your MySQL database, including process list.
If you are behind a firewall, try using
show full processlist
However, I think this will not really help.
I would assume that you are using PHP - MySQL to serve out web pages. So this means that you will mostly find that the MySQL connections are made from PHP. To see how many apache threads are running at one time. You can try:
ps aux |grep httpd |wc -l
If you have many more threads on apache, connecting to MySQL, then you know you have a problem.
You mentioned that you have a busy site, therefore, therefore the real answer to your problem is to cache your content, probably using memcached. The idea is to reduce the hits to your MySQL server. Your server has plenty of RAM and perfect for memcached.
This idea is reuse the content for a certain amount of time depending if the content needs freshness:
<?php
$cachedContent = $memcache->get("cacheKey");
if (!$cachedContent) {
// retrieve from MySQL and formulate HTML here
// you can use obstart so that you can reuse your previous code
ob_start();
// your previous code here
// echo or
?>
<div>
previous generated content from mysql
</div>
<?php
// now cachedContent contains your previous generated HTML
$cachedContent = ob_get_contents();
// set content into memcache
$memcache->set("cacheKey", $cachedContent, false, 1800);
// clear the buffer
ob_end_flush();
}
echo $cachedContent;
?>
You need to find which contents to cache first. Good places to start are:
Inefficient bits on the index.php page (I assume this will be one of the most hit page)
Check your GA for most hit pages.
Check your MySQL slow queries and cache those contents.
Add the below variables in your my.cnf :
If you are going to use only MyISAM engine below variables will give the best result according to your Hardware configuration .
max_allowed_packet = 1M
table_open_cache = 250
sort_buffer_size = 2M
thread_stack = 128K
join_buffer_size = 1M
query_cache_limit = 400k
query_cache_size = 300M
key_buffer_size = 5G
read_buffer_size = 2M
read_rnd_buffer_size = 2M
bulk_insert_buffer_size = 8M
myisam_sort_buffer_size = 8M
myisam_max_sort_file_size = 6G
myisam_recover=FORCE,BACKUP
But depends on your DB size and how your application is accessing(fetching) the data, we can modify the above variables.
Reduce the wait_timeout=30.
Regarding this really i dont have any clue :( ..
Connections _________________
Max used 251 of 250 %Max: 100.40 Total 748.71k 3.5/s
SHOW PROCESSLIST\g
SHOULD PROVIDE THE LIST OF PROCESS ARE CONNECTED TO DB IN ANY STATE (SLEEP/READING..... ETC.,)
Add the above variables in your my.cnf and restart the server .
ps axuw| grep mysql indicates only MySQL process, but if I run htop I can see 10 rows each one of them with a separate PID. So I wonder if they are threads or processes that for some reason I cannot see using ps.
Would it make any sense to try to limit them to two on my development machine, where I don't need concurrent access of many clients.
BTW Running on Ubuntu 8.10
You can set the max number of threads in your my.ini like this:
max_connections=2
However you might also want to set this:
thread_cache_size=1
The thread cache controls how many it keeps open even when nothing is happening.
MySQL does use threads, ps can see them if you run ps -eLf.
That said, I wouldn't worry about it - dormant threads use almost no resources whatsoever, and if you constrain the server too much it's bound to come back and bite you on the backside sometime later when you've forgotten that you did it.
There is few configuration settings in /etc/mysql/my.cnf that would impact memory usage.
Following settings:
key_buffer = 8M
max_connections = 30
query_cache_size = 8M
query_cache_limit = 512K
thread_stack = 128K
should drastically reduce the memory usage of mysql.
read more here: http://opensourcehacker.com/2011/03/31/reducing-mysql-memory-usage-on-ubuntu-debian-linux/
I was seeking for MySQL config stuff, then I saw this question.... Nothing to do with MySQL, am I right ?
If the main objective is to see the result of a custom command, you can use "watch" with the following syntax (available on most linux systems) :
watch "ps axuw| grep mysql"
It will run the command each 2 seconds and display the output, it is a very very useful command.
-> See the doc/man to see how it's powerful ;)