問題描述

我知道這里有很多類似的問題，也有很多結果，當我用谷歌搜索時，但沒有一個能回答我的問題.我讀了這個，這個，這個 和 this 但它們都不適合我.我不談論任何鎖，我不想使用 MySQL C++ 連接器來做到這一點，只是 C API.

I know there are lots of similar questions here, also there are lots of results, when I google it, but none of them answers my question. I read this, this, this and this but none of them works for me. I don't talk about any locks, I don't wanna do this using MySQL c++ connector, just the C API.

此外，這里非常重要的是:我在 LINUX 上執(zhí)行此操作.為什么我提到這個?因為在 mysql_options 的文檔中:

Also, what is very important here: I do this on LINUX. Why I mention this? Because in the documentation for mysql_options:

MYSQL_OPT_READ_TIMEOUT - ...This option works only for 
TCP/IP connections and, prior to MySQL 5.0.25, only for Windows.

MYSQL_OPT_WRITE_TIMEOUT- ... This option works only for 
TCP/IP connections and, prior to MySQL 5.0.25, only for Windows

那么，有沒有辦法為 5.0.25 之前的版本設置查詢超時?

So, is there any way to set a query timeout for versions, prior 5.0.25?

我的 MySQL 版本:

My MySQL version:

[root@xxx kiril]# mysql --version
mysql  Ver 14.12 Distrib 5.0.22, for redhat-linux-gnu (i686) using readline 5.0

至少，有沒有辦法取消查詢?我可以作為不同的線程啟動一個計時器，但是當它到期時..我可以以某種方式取消查詢嗎?

At least, is there any way to cancel a query? I can start a timer as different thread, but when it expires.. can I cancel the query somehow?

推薦答案

好的，我找到了解決方案.感謝 Will 和 PRR(我的同事).

Okay, I found a solution.. Thanks to Will and PRR( my co-worker ).

我無法在每個查詢上啟動一個新線程，因為這是一個實時應用程序，應該每秒處理 1000 多條消息..(無論如何，感謝 R.. 的想法).

I cannot start a new thread on each query, as this is a real-time application, that is supposed to process 1000+ messages per second..(anyway, thanks to R.. for the idea).

此外，無法通過庫終止連接，也無法取消/終止查詢，因為問題出在數(shù)據(jù)庫服務器上..

Also, it was not possible to terminate the connection through the library, nor to cancel/kill the query, as the problem was in the DB server..

這是一個蠻力解決方案，但比 _EXIT( FAILURE ) 更好:這是相關問題:如何在 Linux 上強制關閉套接字?" - 所以，我只是使用系統(tǒng)調用關閉了套接字.

And here's a brute-force solution, but still much better that _EXIT( FAILURE ): Here's the related question: "How to force closing socket on Linux?" - so, I just closed the socket using a system call.

重要提示:(感謝 Will) - 事實證明，我們的 MySQL 庫包裝器具有故障安全"標志，因此在關閉的套接字(或其他嚴重錯誤)上，它會嘗試以解決"問題，因此在我的情況下，它會自行重新打開套接字.所以，我剛剛關閉了這個選項，現(xiàn)在一切都很好 - 執(zhí)行因異常而終止 - 這是執(zhí)行此操作的最軟"方式.
這當然應該通過另一個線程來完成 - 例如一個計時器.

Important NOTE: (thanks Will) - It turned out, that our MySQL library wrapper has s "fail-safe" flag, so that on closed socket (or other critical error), it tries to "solve" the problem, so it reopens the socket, by itself, in my case. So, I just turned off this option and everything is fine now - the execute is terminated because of an exception - this is the "softest" way to do this.
This should be done through another thread, of course - a timer, for example.

超時對于 5.0.25 之后的版本確實有效.但是，至少在 RHEL4 和 RHEL5 上，由于某種原因，超時時間增加了三倍！例如，如果某些超時設置為 20 秒，則實際超時為 ~60 秒..
此外，另一件重要的事情是，這些超時(與任何其他選項一樣)必須設置 after mysql_init 和 before> mysql_connect 或 mysql_real_connect.

The timeouts are really working for versions after 5.0.25. But, at least on RHEL4 and RHEL5, the timeouts are tripled for some reason! For example, if some of the timeouts is set to 20sec, the real timeout is ~60sec..
Also, another important thing is, that these timeouts(as any other options) MUST be set after mysql_init and before mysql_connect or mysql_real_connect.

這篇關于如何使用 C API 為 MySQL 查詢設置超時的文章就介紹到這了，希望我們推薦的答案對大家有所幫助，也希望大家多多支持html5模板網(wǎng)！