Faster installs by changing DMG compression from BZip2 to LZFSE #172
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Significantly improves extract performance, and supported in macOS 10.11+
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I'm happy to do side-by-side timing/comparison if someone can produce a LZFSE compressed DMG. |
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Installing QGIS 3.32 from the macOS DMG file is painfully slow: several minutes for the 3GB of files on an idle M1 Max MBP with 32GB of memory, running macOS 13.4. Neither disk load or memory usage is high.
Sampling the diskimages-helper process in Activity Monitor reveals most time is sitting in the BZ2 decompressor. I think the BZip compression is the culprit — I'm not sure if this is Apple Silicon specific or applies to Intel as well. I've noticed the same issue on previous releases/installs too.
Process sample of `diskimages-helper`
Analysis of sampling diskimages-helper (pid 53419) every 1 millisecond Process: diskimages-helper [53419] Path: /System/Library/PrivateFrameworks/DiskImages.framework/Versions/A/Resources/diskimages-helper Load Address: 0x100e48000 Identifier: diskimages-helper Version: 628.100.8 Code Type: ARM64E Platform: macOS Parent Process: ??? [1]Date/Time: 2023-06-29 2:57:58.181 pm +0200
Launch Time: 2023-06-29 2:52:09.505 pm +0200
OS Version: macOS 13.4.1 (22F82)
Report Version: 7
Analysis Tool: /usr/bin/sample
Physical footprint: 14.5M
Physical footprint (peak): 17.0M
Idle exit: untracked
Call graph:
2365 Thread_4127041 DispatchQueue_1: com.apple.main-thread (serial)
+ 2365 start (in dyld) + 2236 [0x182f07f28]
+ 2365 ??? (in diskimages-helper) load address 0x100e48000 + 0x7684 [0x100e4f684]
+ 2365 -[NSRunLoop(NSRunLoop) runMode:beforeDate:] (in Foundation) + 212 [0x1842b5fcc]
+ 2365 CFRunLoopRunSpecific (in CoreFoundation) + 612 [0x18333c4b8]
+ 2365 __CFRunLoopRun (in CoreFoundation) + 1208 [0x18333d0c4]
+ 2365 __CFRunLoopServiceMachPort (in CoreFoundation) + 160 [0x18333e7e4]
+ 2365 mach_msg (in libsystem_kernel.dylib) + 24 [0x183220290]
+ 2365 mach_msg_overwrite (in libsystem_kernel.dylib) + 604 [0x183228b78]
+ 2365 mach_msg2_internal (in libsystem_kernel.dylib) + 80 [0x183232240]
+ 2365 mach_msg2_trap (in libsystem_kernel.dylib) + 8 [0x18321ff14]
2365 Thread_4129455
2365 thread_start (in libsystem_pthread.dylib) + 8 [0x18325ada0]
2365 _pthread_start (in libsystem_pthread.dylib) + 148 [0x18325ffa8]
2365 NSThread__start (in Foundation) + 716 [0x1842af54c]
2365 ??? (in diskimages-helper) load address 0x100e48000 + 0xdd88 [0x100e55d88]
2057 ??? (in diskimages-helper) load address 0x100e48000 + 0xe568 [0x100e56568]
! 2057 ??? (in diskimages-helper) load address 0x100e48000 + 0xe900 [0x100e56900]
! 2056 CUDIFDiskImage::readSectors(long long, long long, long long*, void*) (in DiskImages) + 736 [0x19921e6a0]
! : 2056 CUDIFDiskImage::__decompressChunkUsingGlobalBuffer(UDIFRun*, unsigned int) (in DiskImages) + 84 [0x199222458]
! : 2030 CUDIFDiskImage::__decompressChunk(UDIFRun*, void*, void*) (in DiskImages) + 236 [0x19921e9ec]
! : | 2030 CBZip2Decompressor::decompressData(void const*, int, void*, int) (in DiskImages) + 48 [0x19925a4ac]
! : | 2024 BZ2_bzBuffToBuffDecompress (in libbz2.1.0.dylib) + 184 [0x18e862318]
! : | + 1487 BZ2_bzDecompress (in libbz2.1.0.dylib) + 3512 [0x18e863200]
Similar bugs elsewhere:
dmgbuild describes the available
formatoptions. QGIS for Mac is currently documented as supporting macOS High Sierra (10.13) or newer, so I thinkULFO(LZFSE) is the newest option that can be used at the moment.