Using gdb info malloc command within xcode (iphone dev)

Question

I'm playing with gdb within xcode debugging an iphone app.

Supposedly, I should be able to use the following command:

info malloc <0xaddress>

see http://www.friday.com/bbum/2010/01/10/using-malloc-to-debug-memory-misuse-in-cocoa/ and strange GDB error unable to trace

I have env vars MallocStackLoggingNoCompact = 1 and NSZombieEnabled = YES set (via the executable in xcode).

However, I am getting this:

2010-10-03 21:29:01.366 memleaktest[10881:307] *** -[one release]: message sent to deallocated instance 0x1646b0
(gdb) info malloc 0x1646b0
Undefined info command: "malloc 0x1646b0".  Try "help info".

What am I missing to run this command? (xcode 3.2.4 and iphone SDK 4.1)

Brynjar · Accepted Answer · 2010-12-15 14:45:04Z

3

Turns out you can only info malloc whilst debugging in the simulator - not on device.

answered Dec 15, 2010 at 14:45

Brynjar

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Bach · Accepted Answer · 2010-12-14 00:02:08Z

1

In Xcode go to Run -> Enable Guard Malloc
Set environment variable MallocStackLoggingNoCompact to YES (as you already did)

to make sure the logs are being written, in the debugger console you should see this message:

malloc: stack logs being written into /tmp/stack-logs.xxxx.MyApp.xxxxxx.index

Now you should be able to:

(gdb) info malloc 0x1646b0

answered Dec 14, 2010 at 0:02

Bach

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3 Comments

Brynjar Over a year ago

Unfortunately this is still not working. A few things I've noticed: a) if I just type 'info' I don't see malloc as possible subcommand. b) I get memtest(2739) malloc: stack logs being written into /private/var/mobile/Applications/1F962F35-9C52-4490-9D22-F5D41DC6AB7C/tmp/stack-logs.2739.memtest.index memtest(2739) malloc: Please issue: cp /private/var/mobile/Applications/1F962F35-9C52-4490-9D22-F5D41DC6AB7C/tmp/stack-logs.2739.memtest.DUY4ZH.link /tmp/ which is a location on my iphone, not my mac

Brynjar Over a year ago

c) the original friday.com article mentions garbage collection I now realise, which is mac only - so does this even apply to the iphone?

Brynjar Over a year ago

OK. This stuff does work for iphone, but only using the simulator. Try and debug on device and you get the weirdness in my previous comments. I found though you did not need guard malloc on. Thanks for the help though.

jianhua · Accepted Answer · 2011-12-28 11:29:52Z

0

Experience the same tough issue, any workable method found? Tough this crash only occurs in device not simulator.

answered Dec 28, 2011 at 11:29

jianhua

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