Why libglInterpose.dylib loaded so slowly?

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Created Jul ’16

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Total pre-main time: 980.70 milliseconds (100.0%)
         dylib loading time:  23.06 milliseconds (2.3%)
        rebase/binding time: 121.75 milliseconds (12.4%)
            ObjC setup time:  76.00 milliseconds (7.7%)
           initializer time: 759.73 milliseconds (77.4%)
           slowest intializers :
             libSystem.B.dylib :  16.47 milliseconds (1.6%)
   libBacktraceRecording.dylib :  26.70 milliseconds (2.7%)
          libglInterpose.dylib : 570.64 milliseconds (58.1%)
                     Camera360 : 208.81 milliseconds (21.2%)

When I use DYLD_PRINT_STATISTICS to measure startup time, The console show libglInterpose.dylib costs 570ms, Why?

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Answer 1

DTS Engineer OP

Apple

Jul ’16

Accepted Answer

Interposing is a debugging technology and thus the cost to load interposing libraries is generally not considered relevant. I recommend you separate your graphics profiling work from your app launch time profiling work.

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Answer 2

cleexiang OP

Jul ’16

Do you means it's only happens for Debug model?

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Answer 3

DTS Engineer OP

Apple

Aug ’16

Do you means it's only happens for Debug model?

I’m not sure what you mean by “Debug model” but I will say that this library is part of Xcode’s debugging infrastructure. I’m not entirely sure what it does (I think it’s part of the OpenGL debugger, but OpenGL isn’t really my thing so I don’t know for sure) but it’s definitely part of Xcode:

$ find /Applications/Xcode.app -name libglInterpose.dylib

/Applications/Xcode.app/Contents/SharedFrameworks/GPUTools.framework/Versions/A/Resources/libglInterpose.dylib

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Quinn “The Eskimo!”
Apple Developer Relations, Developer Technical Support, Core OS/Hardware

let myEmail = "eskimo" + "1" + "@apple.com"

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