hammerspoon: Memory leak in hs.osascript

I noticed recently that Hammerspoon’s memory footprint on my computer seemed to be growing over time. After doing some investigating using lua-mtrace I tracked down the issue to a line in one of my spoons that calls hs.osascript.javascript.

Here’s a minimal line of code to run in the Hammerspoon console to reproduce the behavior:

test = hs.timer.doEvery(0.5, function() hs.osascript.javascript("") end)

If you open Activity Monitor and go to the Memory tab, you’ll see that Hammerspoon’s memory footprint grows as this timer is running. Running test:stop() to stop the timer stops the memory footprint from increasing.

When the timer is running the lua-mtrace log fills up with lines like this,

@ ....app/Contents/Resources/extensions/hs/osascript/init.lua:101 + 0x600002ad59f0 0x50 s

which corresponds to this line,

local ok, object, descriptor = module._osascript(source, "JavaScript")

which calls the runosascript() function in the internal.m file for the module.

Profiling with Xcode using Instruments confirms this. Here’s the “Heaviest Stack Trace” for runosascript() after running the timer for a minute or so, in case that’s helpful:

  56 libdyld.dylib   86.81 MB     start
  55 Hammerspoon   86.81 MB     main /Users/malo/Documents/Code/Hammerspoon/hammerspoon/Hammerspoon/MJAppDelegate.m:364
  54 AppKit   86.81 MB     NSApplicationMain
  53 AppKit   85.24 MB     -[NSApplication run]
  52 AppKit   83.46 MB     -[NSApplication(NSEvent) _nextEventMatchingEventMask:untilDate:inMode:dequeue:]
  51 AppKit   83.36 MB     _DPSNextEvent
  50 HIToolbox   65.46 MB     _BlockUntilNextEventMatchingListInModeWithFilter
  49 HIToolbox   65.46 MB     ReceiveNextEventCommon
  48 HIToolbox   65.46 MB     RunCurrentEventLoopInMode
  47 CoreFoundation   65.38 MB     CFRunLoopRunSpecific
  46 CoreFoundation   65.04 MB     __CFRunLoopRun
  45 CoreFoundation   29.00 MB     __CFRunLoopDoTimers
  44 CoreFoundation   29.00 MB     __CFRunLoopDoTimer
  43 CoreFoundation   29.00 MB     __CFRUNLOOP_IS_CALLING_OUT_TO_A_TIMER_CALLBACK_FUNCTION__
  42 Foundation   28.86 MB     __NSFireTimer
  41 internal.so   28.86 MB     -[HSTimer callback:] /Users/malo/Documents/Code/Hammerspoon/hammerspoon/extensions/timer/internal.m:51
  40 LuaSkin   28.86 MB     -[LuaSkin protectedCallAndTraceback:nresults:] /Users/malo/Documents/Code/Hammerspoon/hammerspoon/LuaSkin/LuaSkin/Skin.m:244
  39 LuaSkin   28.86 MB     lua_pcallk /Users/malo/Documents/Code/Hammerspoon/hammerspoon/LuaSkin/lua-5.3.5/src/lapi.c:969
  38 LuaSkin   28.86 MB     luaD_pcall /Users/malo/Documents/Code/Hammerspoon/hammerspoon/LuaSkin/lua-5.3.5/src/ldo.c:746
  37 LuaSkin   28.86 MB     luaD_rawrunprotected /Users/malo/Documents/Code/Hammerspoon/hammerspoon/LuaSkin/lua-5.3.5/src/ldo.c:156
  36 LuaSkin   28.86 MB     luai_objcttry /Users/malo/Documents/Code/Hammerspoon/hammerspoon/LuaSkin/LuaSkin/lobjectivec_exceptions.m:84
  35 LuaSkin   28.86 MB     f_call /Users/malo/Documents/Code/Hammerspoon/hammerspoon/LuaSkin/lua-5.3.5/src/lapi.c:943
  34 LuaSkin   28.86 MB     luaD_callnoyield /Users/malo/Documents/Code/Hammerspoon/hammerspoon/LuaSkin/lua-5.3.5/src/ldo.c:526
  33 LuaSkin   28.86 MB     luaD_call /Users/malo/Documents/Code/Hammerspoon/hammerspoon/LuaSkin/lua-5.3.5/src/ldo.c:516
  32 LuaSkin   28.86 MB     luaV_execute /Users/malo/Documents/Code/Hammerspoon/hammerspoon/LuaSkin/lua-5.3.5/src/lvm.c:1134
  31 LuaSkin   28.86 MB     luaD_precall /Users/malo/Documents/Code/Hammerspoon/hammerspoon/LuaSkin/lua-5.3.5/src/ldo.c:451
  30 internal.so   28.86 MB     runosascript /Users/malo/Documents/Code/Hammerspoon/hammerspoon/extensions/osascript/internal.m:26
  29 OSAKit   28.79 MB     -[OSAScript compileAndReturnError:]
  28 OpenScripting   28.33 MB     OSACompile
  27 JavaScript   28.07 MB     JavaScriptComponent
  26 CoreFoundation   28.07 MB     -[NSInvocation invoke]
  25 CoreFoundation   28.07 MB     __invoking___
  24 JavaScriptOSA   28.07 MB     -[JSStorage(JSProcedures) compileScriptData:modeFlags:scriptID:]
  23 JavaScriptOSA   28.07 MB     -[JSStorage addScript:]
  22 JavaScriptOSA   28.00 MB     -[JSStorageScriptContext initWithScript:]
  21 JavaScriptAppleEvents   28.00 MB     JSAEContextSetup
  20 JavaScriptAppleEvents   26.96 MB     JSAEExports
  19 JavaScriptAppleEvents   14.77 MB     JSAEApplicationConstructor
  18 JavaScriptAppleEvents   14.02 MB     JSAEApplicationPrototypeCreate
  17 JavaScriptAppleEvents    8.09 MB     JSAELibraryConstructor
  16 JavaScriptAppleEvents    7.60 MB     JSAELibraryPrototypeCreate
  15 JavaScriptAppleEvents    6.31 MB     JSAEObjectSpecifierConstructor
  14 JavaScriptAppleEvents    6.07 MB     -[JSValue(DefineProperties) defineProperties:]
  13 JavaScriptCore    6.07 MB     -[JSValue invokeMethod:withArguments:]
  12 JavaScriptCore    6.07 MB     objectToValue(JSContext*, objc_object*)
  11 JavaScriptCore    6.07 MB     ObjcContainerConvertor::convert(objc_object*)
  10 JavaScriptCore    6.07 MB     objectToValueWithoutCopy(JSContext*, objc_object*)
   9 JavaScriptCore    6.07 MB     -[JSContext(Internal) wrapperForObjCObject:]
   8 JavaScriptCore    6.07 MB     -[JSWrapperMap jsWrapperForObject:inContext:]
   7 JavaScriptCore    6.07 MB     -[JSObjCClassInfo wrapperForObject:inContext:]
   6 JavaScriptCore    3.24 MB     -[JSContext(Internal) wrapperForJSObject:]
   5 JavaScriptCore    3.24 MB     -[JSWrapperMap objcWrapperForJSValueRef:inContext:]
   4 Foundation    3.24 MB     -[NSConcreteMapTable setObject:forKey:]
   3 Foundation    3.21 MB     -[NSConcreteMapTable grow]
   2 Foundation    1.61 MB     allocateCollectableUnscannedStorage
   1 libsystem_malloc.dylib    1.61 MB     malloc
   0 libsystem_malloc.dylib    1.61 MB     malloc_zone_malloc