Rechercher dans le manuel MySQL
B.4.2.10 Communication Errors and Aborted Connections
If connection problems occur such as communication errors or aborted connections, use these sources of information to diagnose problems:
The error log. See Section 5.4.2, “The Error Log”.
The general query log. See Section 5.4.3, “The General Query Log”.
The
Aborted_
andxxx
Connection_errors_
status variables. See Section 5.1.10, “Server Status Variables”.xxx
The host cache, which is accessible using the Performance Schema
host_cache
table. See Section 8.12.4.2, “DNS Lookup Optimization and the Host Cache”, and Section 26.12.18.1, “The host_cache Table”.
If the log_error_verbosity
system variable is set to 3, you might find messages like this
in your error log:
[Note] Aborted connection 854 to db: 'employees' user: 'josh'
If a client is unable even to connect, the server increments
the Aborted_connects
status
variable. Unsuccessful connection attempts can occur for the
following reasons:
A client attempts to access a database but has no privileges for it.
A client uses an incorrect password.
A connection packet does not contain the right information.
It takes more than
connect_timeout
seconds to obtain a connect packet. See Section 5.1.8, “Server System Variables”.
If these kinds of things happen, it might indicate that someone is trying to break into your server! If the general query log is enabled, messages for these types of problems are logged to it.
If a client successfully connects but later disconnects
improperly or is terminated, the server increments the
Aborted_clients
status
variable, and logs an Aborted
connection message to the error log. The cause can
be any of the following:
The client program did not call
mysql_close()
before exiting.The client had been sleeping more than
wait_timeout
orinteractive_timeout
seconds without issuing any requests to the server. See Section 5.1.8, “Server System Variables”.The client program ended abruptly in the middle of a data transfer.
Other reasons for problems with aborted connections or aborted clients:
The
max_allowed_packet
variable value is too small or queries require more memory than you have allocated for mysqld. See Section B.4.2.9, “Packet Too Large”.Use of Ethernet protocol with Linux, both half and full duplex. Some Linux Ethernet drivers have this bug. You should test for this bug by transferring a huge file using FTP between the client and server machines. If a transfer goes in burst-pause-burst-pause mode, you are experiencing a Linux duplex syndrome. Switch the duplex mode for both your network card and hub/switch to either full duplex or to half duplex and test the results to determine the best setting.
A problem with the thread library that causes interrupts on reads.
Badly configured TCP/IP.
Faulty Ethernets, hubs, switches, cables, and so forth. This can be diagnosed properly only by replacing hardware.
Document created the 26/06/2006, last modified the 26/10/2018
Source of the printed document:https://www.gaudry.be/en/mysql-rf-communication-errors.html
The infobrol is a personal site whose content is my sole responsibility. The text is available under CreativeCommons license (BY-NC-SA). More info on the terms of use and the author.
References
These references and links indicate documents consulted during the writing of this page, or which may provide additional information, but the authors of these sources can not be held responsible for the content of this page.
The author This site is solely responsible for the way in which the various concepts, and the freedoms that are taken with the reference works, are presented here. Remember that you must cross multiple source information to reduce the risk of errors.