CODEWITHSUNDEEP
objective-ciphonemultithreading
jowie
jowie

Reputation: 8068

What can I do if two detached threads overlap each other? queue

I'm not very 'up' on multi-threading, but I've been using detachNewThreadSelector in a couple of places to access data in a database. Unfortunately, on slower devices the first request may still be happening when I call the second... Which naturally causes a crash because both are calling the same method (which is obviously not thread-safe).

What is the best way to go about sorting a bug like this? Can I somehow queue them so that the second thread doesn't start until the first one has finished?

Thanks!

Upvotes: 0

Views: 341

Answers (2)

TheBlack
TheBlack

Reputation: 1245

To extend ranos answer a bit, be sure to add operations from the same thread because if you add several NSOperations from several threads, they will run concurrently, even though maxConcurrentOperationCount on NSOperationQueue is set to 1.

Upvotes: 0

rano
rano

Reputation: 5676

You may want to have a look at NSOperation and NSOperationQueue which is an abstraction for a queue of tasks that can be run asynchronously from the main thread. If you want the NSOperationQueue to run just a NSOperation at a time (so to wait after the current task is compleate before firing the next one) you can just set the maxConcurrentOperationCount property of the queue to 1

Upvotes: 2

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