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I'm running a server at my office to process some files and report the results to a remote MySQL server.
The files processing takes some time and the process dies halfway through with the following error:
2006, MySQL server has gone away
I've heard about the MySQL setting, wait_timeout, but do I need to change that on the server at my office or the remote MySQL server?
I have encountered this a number of times and I've normally found the answer to be a very low default setting of max_allowed_packet.
Raising it in /etc/my.cnf (under [mysqld]) to 8 or 16M usually fixes it. (The default in MySql 5.7 is 4194304, which is 4MB.)
[mysqld]
max_allowed_packet=16M
Note: Just create the line if it does not exist
Note: This can be set on your server as it's running.
Note: On Windows you may need to save your my.ini or my.cnf file with ANSI not UTF-8 encoding.
Use set global max_allowed_packet=104857600. This sets it to 100MB.
I had the same problem but changeing max_allowed_packet in the my.ini/my.cnf file under [mysqld] made the trick.
add a line
max_allowed_packet=500M
now restart the MySQL service once you are done.
I used following command in MySQL command-line to restore a MySQL database which size more than 7GB, and it works.
set global max_allowed_packet=268435456;
It may be easier to check if the connection exists and re-establish it if needed.
See PHP:mysqli_ping for info on that.
There are several causes for this error.
MySQL/MariaDB related:
wait_timeout - Time in seconds that the server waits for a connection to become active before closing it.
interactive_timeout - Time in seconds that the server waits for an interactive connection.
max_allowed_packet - Maximum size in bytes of a packet or a generated/intermediate string. Set as large as the largest BLOB, in multiples of 1024.
Example of my.cnf:
[mysqld]
# 8 hours
wait_timeout = 28800
# 8 hours
interactive_timeout = 28800
max_allowed_packet = 256M
Server related:
Your server has full memory - check info about RAM with free -h
Framework related:
Check settings of your framework. Django for example use CONN_MAX_AGE (see docs)
How to debug it:
Check values of MySQL/MariaDB variables.
with sql: SHOW VARIABLES LIKE '%time%';
command line: mysqladmin variables
Turn on verbosity for errors:
MariaDB: log_warnings = 4
MySQL: log_error_verbosity = 3
Check docs for more info about the error
Error: 2006 (CR_SERVER_GONE_ERROR)
Message: MySQL server has gone away
Generally you can retry connecting and then doing the query again to solve this problem - try like 3-4 times before completely giving up.
I'll assuming you are using PDO. If so then you would catch the PDO Exception, increment a counter and then try again if the counter is under a threshold.
If you have a query that is causing a timeout you can set this variable by executing:
SET ##GLOBAL.wait_timeout=300;
SET ##LOCAL.wait_timeout=300; -- OR current session only
Where 300 is the number of seconds you think the maximum time the query could take.
Further information on how to deal with Mysql connection issues.
EDIT: Two other settings you may want to also use is net_write_timeout and net_read_timeout.
In MAMP (non-pro version) I added
--max_allowed_packet=268435456
to ...\MAMP\bin\startMysql.sh
Credits and more details here
If you are using xampp server :
Go to xampp -> mysql -> bin -> my.ini
Change below parameter :
max_allowed_packet = 500M
innodb_log_file_size = 128M
This helped me a lot :)
This error is occur due to expire of wait_timeout .
Just go to mysql server check its wait_timeout :
mysql> SHOW VARIABLES LIKE 'wait_timeout'
mysql> set global wait_timeout = 600 # 10 minute or maximum wait time
out you need
http://sggoyal.blogspot.in/2015/01/2006-mysql-server-has-gone-away.html
I was getting this same error on my DigitalOcean Ubuntu server.
I tried changing the max_allowed_packet and the wait_timeout settings but neither of them fixed it.
It turns out that my server was out of RAM. I added a 1GB swap file and that fixed my problem.
Check your memory with free -h to see if that's what's causing it.
On windows those guys using xampp should use this path xampp/mysql/bin/my.ini and change max_allowed_packet(under section[mysqld])to your choice size.
e.g
max_allowed_packet=8M
Again on php.ini(xampp/php/php.ini) change upload_max_filesize the choice size.
e.g
upload_max_filesize=8M
Gave me a headache for sometime till i discovered this. Hope it helps.
It was RAM problem for me.
I was having the same problem even on a server with 12 CPU cores and 32 GB RAM. I researched more and tried to free up RAM. Here is the command I used on Ubuntu 14.04 to free up RAM:
sync && echo 3 | sudo tee /proc/sys/vm/drop_caches
And, it fixed everything. I have set it under cron to run every hour.
crontab -e
0 * * * * bash /root/ram.sh;
And, you can use this command to check how much free RAM available:
free -h
And, you will get something like this:
total used free shared buffers cached
Mem: 31G 12G 18G 59M 1.9G 973M
-/+ buffers/cache: 9.9G 21G
Swap: 8.0G 368M 7.6G
In my case it was low value of open_files_limit variable, which blocked the access of mysqld to data files.
I checked it with :
mysql> SHOW VARIABLES LIKE 'open%';
+------------------+-------+
| Variable_name | Value |
+------------------+-------+
| open_files_limit | 1185 |
+------------------+-------+
1 row in set (0.00 sec)
After I changed the variable to big value, our server was alive again :
[mysqld]
open_files_limit = 100000
This generally indicates MySQL server connectivity issues or timeouts.
Can generally be solved by changing wait_timeout and max_allowed_packet in my.cnf or similar.
I would suggest these values:
wait_timeout = 28800
max_allowed_packet = 8M
If you are using the 64Bit WAMPSERVER, please search for multiple occurrences of max_allowed_packet because WAMP uses the value set under [wampmysqld64] and not the value set under [mysqldump], which for me was the issue, I was updating the wrong one. Set this to something like max_allowed_packet = 64M.
Hopefully this helps other Wampserver-users out there.
There is an easier way if you are using XAMPP.
Open the XAMPP control panel, and click on the config button in mysql section.
Now click on the my.ini and it will open in the editor. Update the max_allowed_packet to your required size.
Then restart the mysql service. Click on stop on the Mysql service click start again. Wait for a few minutes.
Then try to run your Mysql query again. Hope it will work.
It's always a good idea to check the logs of the Mysql server, for the reason why it went away.
It will tell you.
MAMP 5.3, you will not find my.cnf and adding them does not work as that max_allowed_packet is stored in variables.
One solution can be:
Go to http://localhost/phpmyadmin
Go to SQL tab
Run SHOW VARIABLES and check the values, if it is small then run with big values
Run the following query, it set max_allowed_packet to 7gb:
set global max_allowed_packet=268435456;
For some, you may need to increase the following values as well:
set global wait_timeout = 600;
set innodb_log_file_size =268435456;
For Vagrant Box, make sure you allocate enough memory to the box
config.vm.provider "virtualbox" do |vb|
vb.memory = "4096"
end
This might be a problem of your .sql file size.
If you are using xampp. Go to the xampp control panel -> Click MySql config -> Open my.ini.
Increase the packet size.
max_allowed_packet = 2M -> 10M
The unlikely scenario is you have a firewall between the client and the server that forces TCP reset into the connection.
I had that issue, and I found our corporate F5 firewall was configured to terminate inactive sessions that are idle for more than 5 mins.
Once again, this is the unlikely scenario.
uncomment the ligne below in your my.ini/my.cnf, this will split your large file into smaller portion
# binary logging format - mixed recommended
# binlog_format=mixed
TO
# binary logging format - mixed recommended
binlog_format=mixed
I found the solution to "#2006 - MySQL server has gone away" this error.
Solution is just you have to check two files
config.inc.php
config.sample.inc.php
Path of these files in windows is
C:\wamp64\apps\phpmyadmin4.6.4
In these two files the value of this:
$cfg['Servers'][$i]['host']must be 'localhost' .
In my case it was:
$cfg['Servers'][$i]['host'] = '127.0.0.1';
change it to:
"$cfg['Servers'][$i]['host']" = 'localhost';
Make sure in both:
config.inc.php
config.sample.inc.php files it must be 'localhost'.
And last set:
$cfg['Servers'][$i]['AllowNoPassword'] = true;
Then restart Wampserver.
To change phpmyadmin user name and password
You can directly change the user name and password of phpmyadmin through config.inc.php file
These two lines
$cfg['Servers'][$i]['user'] = 'root';
$cfg['Servers'][$i]['password'] = '';
Here you can give new user name and password.
After changes save the file and restart WAMP server.
I got Error 2006 message in different MySQL clients software on my Ubuntu desktop. It turned out that my JDBC driver version was too old.
I had the same problem in docker adding below setting in docker-compose.yml:
db:
image: mysql:8.0
command: --wait_timeout=800 --max_allowed_packet=256M --character-set-server=utf8 --collation-server=utf8_general_ci --default-authentication-plugin=mysql_native_password
volumes:
- ./docker/mysql/data:/var/lib/mysql
- ./docker/mysql/dump:/docker-entrypoint-initdb.d
ports:
- 3306:3306
environment:
MYSQL_ROOT_PASSWORD: ${MYSQL_ROOT_PASSWORD}
MYSQL_DATABASE: ${MYSQL_DATABASE}
MYSQL_USER: ${MYSQL_USER}
MYSQL_PASSWORD: ${MYSQL_PASSWORD}
I also encountered this error. But even with the increased max_allowed_packet or any increase of value in the my.cnf, the error still persists.
What I did is I troubleshoot my database:
I checked the tables where the error persists
Then I checked each row
There are rows that are okay to fetch and there are rows where the error only shows up
It seems that there are value in these rows that is causing this error
But even by selecting only the primary column, the error still shows up (SELECT primary_id FROM table)
The solution that I thought of is to reimport the database. Good thing is I have a backup of this database. But I only dropped the problematic table, then import my backup of this table. That solved my problem.
My takeaway of this problem:
Always have a backup of your database. Either manually or thru CRON job
I noticed that there are special characters in the affected rows. So when I recovered the table, I immediately changed the collation of this table from latin1_swedish_ci to utf8_general_ci
My database was working fine before then my system suddenly encountered this problem. Maybe it also has something to do with the upgrade of the MySQL database by our hosting provider. So frequent backup is a must!
Just in case this helps anyone:
I got this error when I opened and closed connections in a function which would be called from several parts of the application.
We got too many connections so we thought it might be a good idea to reuse the existing connection or throw it away and make a new one like so:
public static function getConnection($database, $host, $user, $password){
if (!self::$instance) {
return self::newConnection($database, $host, $user, $password);
} elseif ($database . $host . $user != self::$connectionDetails) {
self::$instance->query('KILL CONNECTION_ID()');
self::$instance = null;
return self::newConnection($database, $host, $user, $password);
}
return self::$instance;
}
Well turns out we've been a little too thorough with the killing and so the processes doing important things on the old connection could never finish their business.
So we dropped these lines
self::$instance->query('KILL CONNECTION_ID()');
self::$instance = null;
and as the hardware and setup of the machine allows it we increased the number of allowed connections on the server by adding
max_connections = 500
to our configuration file. This fixed our problem for now and we learned something about killing mysql connections.
For users using XAMPP, there are 2 max_allowed_packet parameters in C:\xampp\mysql\bin\my.ini.
This error happens basically for two reasons.
You have a too low RAM.
The database connection is closed when you try to connect.
You can try this code below.
# Simplification to execute an SQL string of getting a data from the database
def get(self, sql_string, sql_vars=(), debug_sql=0):
try:
self.cursor.execute(sql_string, sql_vars)
return self.cursor.fetchall()
except (AttributeError, MySQLdb.OperationalError):
self.__init__()
self.cursor.execute(sql_string, sql_vars)
return self.cursor.fetchall()
It mitigates the error whatever the reason behind it, especially for the second reason.
If it's caused by low RAM, you either have to raise database connection efficiency from the code, from the database configuration, or simply raise the RAM.
For me it helped to fix one's innodb table's corrupted index tree. I localized such a table by this command
mysqlcheck -uroot --databases databaseName
result
mysqlcheck: Got error: 2013: Lost connection to MySQL server during query when executing 'CHECK TABLE ...
as followed I was able to see only from the mysqld logs /var/log/mysqld.log which table was causing troubles.
FIL_PAGE_PREV links 2021-08-25T14:05:22.182328Z 2 [ERROR] InnoDB: Corruption of an index tree: table `database`.`tableName` index `PRIMARY`, father ptr page no 1592, child page no 1234'
The mysqlcheck command did not fix it, but helped to unveil it.
Ultimately I fixed it as followed by a regular mysql command from a mysql cli
OPTIMIZE table theCorruptedTableNameMentionedAboveInTheMysqld.log
I'm using MySQL Community Server 5.5 with PHP 5.3.3 on a Windows Server 2008 platform.
I have set up per user resources limits, particularly a limit related to the queries run by a DB user within one hour. I have read this document and it is very interesting but always it doesn't work for me.
http://dev.mysql.com/doc/refman/5.5/en/user-resources.html
When I run a query via mysql command line tool (mysql.exe) the limit works properly and if the queries limit per hour was 7, after 7 queries within one hour I receive the error:
ERROR 1226 (42000): User 'user' has
exceeded the 'max_questions' resource
(current value: 7)
This above is the wanted behavior.
When I run a query via PHP (The user I have used to connect to the DB is the same above), the queries limit doesn't work: the same user via php can run all the queries it wants and without any limit. And if I come back on the mysql command line above the counter seems to be reset (even if the hour hasn't elapsed) : I can run 7 queries within an hour too.
I think this isn't the wanted behaviour. It seems that PHP resets the counter and doesn't trigger the queries limit.
PS: The 'user' owns only SELECT,INSERT,UPDATE,DELETE privileges and in the PHP code there isn't any SQL code as FLUSH USER_RESOURCES that the user 'user' couldn't have run (because RELOAD privilege isn't assigned to the user)
Thanks in advance
Check this tip,
how many users do you have in your mysql with the same name..(remember not only the name but the host where is permited to connect the user is specified in mysql ). **VERY IMPORTANT.
user#%
user#127.0.0.1
user#localhost
user#172.35.20.12
each one of them are not the same, if you have any limit rule do you like to use, so, you must assign limitations to the user#wherever you want the limintation. (all of them, if you have problems **think is your case).
Recomendation: create a specific user for WEB PHP (only one user#host must be created) , instead using a generic user with may have several users#hosts assigned.
like phpuser#'localhost' typically is enough.
I think you are doing little mistake,
Please check for the host in your mysql_connect function into php.
if your host is IP address then you need to assign the resource limit to username#yourip or username#%
If you are running through the command line then you are login from username#localhost and you have assign the limit to the same user.
Please try my above tricks and let me know if you are having problem still ?
Happy coding....
I have solved (partially) the problem.
The problem occurs only when the query including the MAX_QUERIES_PER_HOUR component includes also one of the following elements different from 0:
MAX_CONNECTIONS_PER_HOUR !=0
MAX_USER_CONNECTIONS !=0;
e.g. the following grant query won't ever cause the error message related to the queries limit achievement in PHP:
GRANT USAGE ON *.* TO 'user'#'localhost'
WITH MAX_QUERIES_PER_HOUR 20
MAX_UPDATES_PER_HOUR 10
MAX_CONNECTIONS_PER_HOUR 5
MAX_USER_CONNECTIONS 2;
Instead the following grant works correctly and MySQL applies the limits correctly.
GRANT USAGE ON *.* TO 'user'#'localhost'
WITH MAX_QUERIES_PER_HOUR 20
MAX_UPDATES_PER_HOUR 10
MAX_CONNECTIONS_PER_HOUR 0
MAX_USER_CONNECTIONS 0;
In short, when the query setting queries limit includes one of the components, MAX_CONNECTIONS_PER_HOUR and MAX_USER_CONNECTIONS different from 0, the limits related to the MAX_QUERIES_PER_HOUR and MAX_UPDATES_PER_HOUR are ignored: my PHP pages can perform all the queries they want. Otherwise the limit is understood and the message
has exceeded the 'max_questions' resource
correctly is showed when the queries limit achievement event occurs.
As I said above the problem doesn't occurs when I use the mysql command line tool. It occurs only when queries are run through PHP pages.
Is there a way to create a new MySQL database, a new MySQL user and give the new user privileges on the new database all using PHP?
EDIT - should be pointed out this is run from 1 server to another, so Server A trying to install a DB/user on Server B
i've got this:
$con = mysql_connect("REMOTE.IP.ADDRESS","root","pass");
mysql_query("CREATE DATABASE ".$db."",$con)or die(mysql_error());
mysql_query("GRANT ALL ON ".$db.".* to ".$user." identified by '".$dbpass."'",$con) or die(mysql_error());
but i'm getting an error on the grant query:
"Access denied for user 'root'#'MY.REMOTE.SERVER.HOST.NAME' to database 'dbname'"
This answer has been edited several times based on new info provided by the OP
Is root actually allowed to connect to the server from the host that you are connecting from? If the error string is returning the canonical name of the server, there's a very good chance that 'localhost' is not pointing to 127.0.0.1 :
"Access denied for user
'root'#'MY.SERVER.HOST.NAME' to
database 'dbname'"
That should echo something like "Access denied for user 'root'#localhost'", not the name of the server.
Try:
$con = mysql_connect("127.0.0.1","root","pass");
Edit (After more information provided in comments)
If you are connecting from a totally different host, you have to tell MySQL user#remote_hostname_or_ip is allowed to connect, and has appropriate privileges to create a database and users.
You can do this rather easily using phpmyadmin (on the MySQL server), or a query like:
CREATE USER 'root'#'192.168.1.1' IDENTIFIED BY PASSWORD 'secret';
GRANT ALL PRIVILEGES ON * . * TO 'root'#'192.168.1.1' IDENTIFIED BY PASSWORD 'secret' WITH GRANT OPTION MAX_QUERIES_PER_HOUR 0 MAX_CONNECTIONS_PER_HOUR 0 MAX_UPDATES_PER_HOUR 0 MAX_USER_CONNECTIONS 0 ;
I would advise not naming this user 'root' , just create a user with all of the global privileges needed. In the example, I used 192.168.1.1, that could easily be a hostname, just make sure DNS is set up appropriately. Specify the host to match exactly as it appears in logs when you connect to the remote server.
You may also want to adjust limits to taste. More information on the CREATE USER syntax can be found here, GRANT here.
Edit
If using MySQL 4 - CREATE is not an option. You would just use GRANT (4.1 Docs On User Management)
Edit
If using C-Panel, just use the API. While yes, it does have its quirks, its easier to maintain stuff that uses it rather than ad-hoc work arounds. A lot of successful applications use it without issue. Like any other API, you need to stay on top of changes when using it.
I believe you'd have to create a connection (with the root user) to an existing database (like mysql) and then run the create query.
You don't see a database connect in this example for the obvious reason: it is supposed that you learned already that any database action requires connect first.
It's the way the books being written: the things from the previous lessons being omitted in the next ones. Or every chapter will be 2 times bigger and you'll never finish the book.
so yes, you need to connect to the database first, using mysql_connect().
to create a user you can use mysql GRANT query
though I am never done it from the script but from the shell only
You would need to connect to the sql server first:
$conn=#mysql_connect(DB_HOST, DB_USER, DB_PASSWORD)
or die("Err:Conn");
Then the query will execute. A lot of shared hosting servers disable the creation of databases via PHP though.
I'd like to ask your help on a longstanding issue with php/mysql connections.
Every time I execute a "SHOW PROCESSLIST" command it shows me about 400 idle (Status: Sleep) connections to the database Server emerging from our 5 Webservers.
That never was much of a problem (and I didn't find a quick solution) until recently traffic numbers increased and since then MySQL reports the "to many connections" Problems repeatedly, even so 350+ of those connections are in "sleep" state. Also a server can't get a MySQL connection even if there are sleeping connection to that same server.
All those connections vanish when an apache server is restated.
The PHP Code used to create the Database connections uses the normal "mysql" Module, the "mysqli" Module, PEAR::DB and Zend Framework Db Adapter. (Different projects). NONE of the projects uses persistent connections.
Raising the connection-limit is possible but doesn't seem like a good solution since it's 450 now and there are only 20-100 "real" connections at a time anyways.
My question:
Why are there so many connections in sleep state and how can I prevent that?
-- Update:
The Number of Apache requests running at a time never exceeds 50 concurrent requests, so i guess there is a problem with closing the connection or apache keeps the port open without a phpscript attached or something (?)
my.cnf in case it's helpful:
innodb_buffer_pool_size = 1024M
max_allowed_packet = 5M
net_buffer_length = 8K
read_buffer_size = 2M
read_rnd_buffer_size = 8M
query_cache_size = 512M
myisam_sort_buffer_size = 128M
max_connections = 450
thread_cache = 50
key_buffer_size = 1280M
join_buffer_size = 16M
table_cache = 2048
sort_buffer_size = 64M
tmp_table_size = 512M
max_heap_table_size = 512M
thread_concurrency = 8
log-slow-queries = /daten/mysql-log/slow-log
long_query_time = 1
log_queries_not_using_indexes
innodb_additional_mem_pool_size = 64M
innodb_log_file_size = 64M
innodb_log_buffer_size = 8M
innodb_flush_log_at_trx_commit = 2
innodb_file_per_table
Basically, you get connections in the Sleep state when :
a PHP script connects to MySQL
some queries are executed
then, the PHP script does some stuff that takes time
without disconnecting from the DB
and, finally, the PHP script ends
which means it disconnects from the MySQL server
So, you generally end up with many processes in a Sleep state when you have a lot of PHP processes that stay connected, without actually doing anything on the database-side.
A basic idea, so : make sure you don't have PHP processes that run for too long -- or force them to disconnect as soon as they don't need to access the database anymore.
Another thing, that I often see when there is some load on the server :
There are more and more requests coming to Apache
which means many pages to generate
Each PHP script, in order to generate a page, connects to the DB and does some queries
These queries take more and more time, as the load on the DB server increases
Which means more processes keep stacking up
A solution that can help is to reduce the time your queries take -- optimizing the longest ones.
The above solutions like run a query
SET session wait_timeout=600;
Will only work until mysql is restarted. For a persistant solution, edit mysql.conf and add after [mysqld]:
wait_timeout=300
interactive_timeout = 300
Where 300 is the number of seconds you want.
Increasing number of max-connections will not solve the problem.
We were experiencing the same situation on our servers. This is what happens
User open a page/view, that connect to the database, query the database, still query(queries) were not finished and user leave the page or move to some other page.
So the connection that was open, will remains open, and keep increasing number of connections, if there are more users connecting with the db and doing something similar.
You can set interactive_timeout MySQL, bydefault it is 28800 (8hours) to 1 hour
SET interactive_timeout=3600
Before increasing the max_connections variable, you have to check how many non-interactive connection you have by running show processlist command.
If you have many sleep connection, you have to decrease the value of the "wait_timeout" variable to close non-interactive connection after waiting some times.
To show the wait_timeout value:
SHOW SESSION VARIABLES LIKE 'wait_timeout';
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| wait_timeout | 28800 |
+---------------+-------+
the value is in second, it means that non-interactive connection still up to 8 hours.
To change the value of "wait_timeout" variable:
SET session wait_timeout=600;
Query OK, 0 rows affected (0.00 sec)
After 10 minutes if the sleep connection still sleeping the mysql or MariaDB drop that connection.
Alright so after trying every solution out there to solve this exact issues on a wordpress blog, I might have done something either really stupid or genius... With no idea why there's an increase in Mysql connections, I used the php script below in my header to kill all sleeping processes..
So every visitor to my site helps in killing the sleeping processes..
<?php
$result = mysql_query("SHOW processlist");
while ($myrow = mysql_fetch_assoc($result)) {
if ($myrow['Command'] == "Sleep") {
mysql_query("KILL {$myrow['Id']}");}
}
?>
So I was running 300 PHP processes simulatenously and was getting a rate of between 60 - 90 per second (my process involves 3x queries). I upped it to 400 and this fell to about 40-50 per second. I dropped it to 200 and am back to between 60 and 90!
So my advice to anyone with this problem is experiment with running less than more and see if it improves. There will be less memory and CPU being used so the processes that do run will have greater ability and the speed may improve.
Look into persistent MySQL connections: I connected using mysqli('p:$HOSTNAME') and had Laravel database.php settings like:
'options' => [
PDO::ATTR_PERSISTENT => true,
],
For some reason, for some time, I believed it was smart to keep connections persistent as I thought my applications would share them. They didn't. They just opened connections and left them unused until they timed out.
After I removed my mad dream of persistency I went from 120-150+ connections from several hosts to only a handful, most of the time actually just one (being the one that runs SHOW PROCESSLIST).
I am using MySQL 5.0 for a site that is hosted by GoDaddy (linux).
I was doing some testing on my web app, and suddenly I noticed that the pages were refreshing really slowly. Finally, after a long wait, I got to a page that said something along the lines of "MySQL Error, Too many connections...", and it pointed to my config.php file which connects to the database.
It has just been me connecting to the database, no other users. On each of my pages, I include the config.php file at the top, and close the mysql connection at the end of the page. There may be several queries in between. I fear that I am not closing mysql connections enough (mysql_close()).
However, when I try to close them after running a query, I receive connection errors on the page. My pages are PHP and HTML. When I try to close a query, it seems that the next one won't connect. Would I have to include config.php again after the close in order to connect?
This error scared me because in 2 weeks, about 84 people start using this web application.
Thanks.
EDIT:
Here is some pseudo-code of my page:
require_once('../scripts/config.php');
<?php
mysql_query..
if(this button is pressed){
mysql_query...
}
if(this button is pressed){
mysql_query...
}
if(this button is pressed){
mysql_query...
}
?>
some html..
..
..
..
..
<?php
another mysql_query...
?>
some more html..
..
..
<?php mysql_close(); ?>
I figured that this way, each time the page opens, the connection opens, and then the connection closes when the page is done loading. Then, the connection opens again when someone clicks a button on the page, and so on...
EDIT:
Okay, so I just got off the phone with GoDaddy. Apparently, with my Economy Package, I'm limited to 50 connections at a time. While my issue today happened with only me accessing the site, they said that they were having some server problems earlier. However, seeing as how I am going to have 84 users for my web app, I should probably upgrade to "Deluxe", which allows for 100 connections at a time. On a given day, there may be around 30 users accessing my site at a time, so I think the 100 would be a safer bet. Do you guys agree?
Shared-hosting providers generally allow a pretty small amount of simultaneous connections for the same user.
What your code does is :
open a connection to the MySQL server
do it's stuff (generating the page)
close the connection at the end of the page.
The last step, when done at the end of the page is not mandatory : (quoting mysql_close's manual) :
Using mysql_close() isn't usually
necessary, as non-persistent open
links are automatically closed at the
end of the script's execution.
But note you probably shouldn't use persistent connections anyway...
Two tips :
use mysql_connect insead of mysql_pconnect (already OK for you)
Set the fourth parameter of mysql_connect to false (already OK for you, as it's the default value) : (quoting the manual) :
If a second call is made to
mysql_connect() with the same
arguments, no new link will be
established, but instead, the link
identifier of the already opened link
will be returned.
The new_link
parameter modifies this behavior and
makes mysql_connect() always open a
new link, even if mysql_connect() was
called before with the same
parameters.
What could cause the problem, then ?
Maybe you are trying to access several pages in parallel (using multiple tabs in your browser, for instance), which will simulate several users using the website at the same time ?
If you have many users using the site at the same time and the code between mysql_connect and the closing of the connection takes lots of time, it will mean many connections being opened at the same time... And you'll reach the limit :-(
Still, as you are the only user of the application, considering you have up to 200 simultaneous connections allowed, there is something odd going on...
Well, thinking about "too many connections" and "max_connections"...
If I remember correctly, max_connections does not limit the number of connections you can open to the MySQL Server, but the total number of connections that can bo opened to that server, by anyone connecting to it.
Quoting MySQL's documentation on Too many connections :
If you get a Too many connections
error when you try to connect to the
mysqld server, this means that all
available connections are in use by
other clients.
The number of connections allowed is
controlled by the max_connections
system variable. Its default value is
100. If you need to support more connections, you should set a larger
value for this variable.
So, actually, the problem might not come from you nor your code (which looks fine, actually) : it might "just" be that you are not the only one trying to connect to that MySQL server (remember, "shared hosting"), and that there are too many people using it at the same time...
... And if I'm right and it's that, there's nothing you can do to solve the problem : as long as there are too many databases / users on that server and that max_connection is set to 200, you will continue suffering...
As a sidenote : before going back to GoDaddy asking them about that, it would be nice if someone could validate what I just said ^^
I had about 18 months of dealing with this (http://ianchanning.wordpress.com/2010/08/25/18-months-of-dealing-with-a-mysql-too-many-connections-error/)
The solutions I had (that would apply to you) in the end were:
tune the database according to MySQLTuner.
defragment the tables weekly based on this post
Defragmenting bash script from the post:
#!/bin/bash
# Get a list of all fragmented tables
FRAGMENTED_TABLES="$( mysql -e `use information_schema; SELECT TABLE_SCHEMA,TABLE_NAME
FROM TABLES WHERE TABLE_SCHEMA NOT IN ('information_schema','mysql') AND
Data_free > 0` | grep -v '^+' | sed 's,t,.,' )"
for fragment in $FRAGMENTED_TABLES; do
database="$( echo $fragment | cut -d. -f1 )"
table="$( echo $fragment | cut -d. -f2 )"
[ $fragment != "TABLE_SCHEMA.TABLE_NAME" ] && mysql -e "USE $database;
OPTIMIZE TABLE $table;" > /dev/null 2>&1
done
Make sure you are not using persistent connections. This is usually a bad idea..
If you've got that .. At the very most you will need to support just as much connections as you have apache processes. Are you able to change the max_connections setting?
Are you completely sure that the database server is completely dedicated to you?
Log on to the datbase as root and use "SHOW PROCESSLIST" to see who's connected. Ideally hook this into your monitoring system to view how many connections there are over time and alert if there are too many.
The maximum database connections can be configured in my.cnf, but watch out for running out of memory or address space.
If you have shell access, use netstat to see how many sockets are opened to your database and where they come from.
On Linux, type:
netstat -n -a |grep 3306
On windows, type:
netstat -n -a |findstr 3306
The solution could one of these, i came across this in a MCQA test, even i did not understood which one is right!
Set this in my.cnf "set-variable=max_connections=200"
Execute the command "SET GLOBALmax_connections = 200"
Use always mysql_connect() function in order to connect to the mysql server
Use always mysql_pconnect() function in order to connect to the mysql server
Followings are possible solutions:
1) Increase the max connection setting by setting the global variable in mysql.
set global max_connection=200;
Note: It will increase the server load.
2) Empty your connection pool as below :
FLUSH HOSTS;
3) check your processList and kill specific processlist if you don't want any of them.
You may refer this :-
article link