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Editorial Team
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Asked: 2026-05-12T12:01:19+00:00

I have an objective-c application for OS X that compares two sqlite DB’s and

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I have an objective-c application for OS X that compares two sqlite DB’s and produces a diff in json format. The db are quite large (10,000 items with many fields). Sometimes this applications runs in about 55 sec(using 95% of the cpu). Sometimes it takes around 8 min (using 12% of the cpu). This is with the same DB’s. When it is only using a small portion of the cpu the rest is available. There does not appear to be anything taking priority over the process. Adding “nice -20” on the command seems to assure I get the cpu usage. My questions are

  1. If nothing else is using the cpu why
    does my app not take advantage of
    it?

  2. Is there something I can do
    programatically to change this?

  3. Is there something I can do to OS X to
    change this?

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1 Answer

  1. Editorial Team

    Question 1:

    Since, I assume, you have to read in the databases from disk, you aren’t making full use of the CPU because your code is blocking on disk reads. On Mac OS X there is a lot of stuff running in the background that doesn’t use a lot of CPU time but does send out a lot of disk reads, like Spotlight.

    Question 2:

    Probably not, other than make the most efficient use of disk access possible.

    Question 3:

    Shut down any other processes that are accessing the disk. This includes many system processes that you really shouldn’t shut down, so I don’t think there’s much you can do here other than try running it on Darwin without all the Mac OS X fanciness.

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