February 2012
Intermediate to advanced
266 pages
8h
English
Content preview from MySQL TroubleshootingBecome an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
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Other Locking Issues
Other resources that can affect your application are internal locks and mutexes acquired when the server executes particular operations. Most of them protect data integrity. With a few exceptions, such as InnoDB mutexes and spin locks, you cannot and should not try to control them, but because a few of them can become visible to user applications, I’ll describe them here.
Transactions can create race conditions and therefore deadlocks, but so can other activities. When the MySQL server starts using a resource such as a file or modifies a variable that is shared between threads, it locks access to the resource to prevent concurrent access to the same resource by other threads. This is done for data consistency. But at the same time, such protection can lead to deadlocks.
These deadlocks are hard to diagnose and theoretically should never happen, but because they have turned up in the past, I’ll describe what to do when you suspect it. As an example, I will create a deadlock of this kind using a test case from a bug report. This bug is not related to troubleshooting a metadata lock (MDL), so I will concentrate on just the debugging aspect, not on the actions that led to the deadlock.
Note
It might seem artificial to illustrate a problem caused by a MySQL bug instead of a user error, but the message is useful. Nobody is insured against hitting a bug, and it is good to be prepared. Forewarned is forearmed.
The symptoms of a “resource” deadlock are the same as for deadlocks ...
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.