Re: passing complex objects between threads
Re: passing complex objects between threads
- Subject: Re: passing complex objects between threads
- From: Eric Hermanson <email@hidden>
- Date: Fri, 24 Apr 2009 21:33:40 -0400
I believe you should use a producer-consumer pattern where the
consumer thread waits on a blocking queue for the incoming object, and
the producer thread passes the fetched object to the blocking queue
after its fetched. There are many examples of producer/consumer on
the web...
- Eric
On Apr 24, 2009, at 9:24 PM, Daniel Child wrote:
I have a Core Data app that imports data via a separate managed
object contexts. Without multithreading, the operation works fine.
But since the import takes over a minute, I want to do the import in
a different thread. The data consists of an archived table of data
with records.
This is my first time attempting to use threads, and the basic
problem I'm having is figuring out the best way to pass the complex
object (the table of records) from one thread to another. Since
there are something like 50,000 records, deep-copying would be ugly.
I thought of three workarounds.
1. Unarchive the table to be parsed while in the second thread so
you have the original, not a copy. Should work, but it's kind of
skirting the issue.
2. Create a global variable and copy the table into it . I tried
this, but the table's records ivar is still not deep-copied.
3. The thread is called by the app controller with thread's owner
set to the app controller itself. i.e. (void) doImportThread: (id)
owner [== self / appController]. Theoretically, I should be able to
cache the table as appController ivar and access it from within the
thread as [owner tableToParse]. I tried this too, and just as with
the global variable approach, the actual records are not available
within the second thread, only the simple ivars.
This must be a common issue with multithreading. Is there an elegant
way to get access to deeper layers of a complex object from within
another thread? i.e. a way to make 2) or 3) above work?
Thanks.
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