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@migueldeicaza @rolfbjarne @slluis
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HeapShot is a profiler to explore live objects in the heap.
HeapShot can either explore one snapshot of memory at a
point, or it can be used to compare the objects between two separate
points in time.
Enabling HeapShot
To use HeapShot, you must run the application to be examined
with the following command line:
mono --profile=heap-shot MyProgram.exe
This activates the `heap-shot' profiler for your application.
HeapShot works by taking snapshots of the heap in your
application on demand. There are two tools used to explore
the heap: heap-shot (a command line tool) and heap-shot-gui (a
graphical user interface for HeapShot).
Using the GUI for HeapShot
Once your program has been started with HeapShot using the
command line option, you can start up heap-shot-gui, this is a
program that allows you to explore your application live.
First click on "Memory Snapshot", and select the process that
you want to explore from the list of processes.
This will trigger Mono to take a snapshot of all the live
objects in your application.
Once you take the snapshot, select it from the right-side
list, this will update the Summary view with information about
the number of objects allocated and the memory consumed:
Name: outfile_0.omap
Object count: 1,043
Total memory: 64,570 bytes
Click on the tab that says "All Objects" to explore the
objects that have been created.
Here you can quickly inspect:
The types that are being created.
Number of instance of the objects created (default sorting)
Memory used by these instances.
Average size of these objects.
There are two possible views:
* Viewing types and which objects they created.
* Viewing objects that reference the current type.
The default mode is to view the types and the object that
instances of that type have created. To view the objects that
keep references to a given type, click on:
"[ ] Inverse references"
At the bottom of the screen.
For each type show, you can break down the objects that are
referenced by this particular object at any given time, for
example, to view the objects that were allocated by
System.Globalization.CultureInfo click on the triangle next to
it, and you will get a list of objects that looks like this:
Instances | Memory Size | Avg Size
System.Globalization.CultureInfo 4 | 464 | 116
string 29 | 1,170 | 40
System.Globalization.CompareInfo 2 | 72 | 36
System.Globalization.TextInfo 2 | 120 | 60
System.Globalization.DateTimeFormatInfo 2 | 352 | 176
System.Globalization.NumberFormatInfo 1 | 152 | 152
Double-clicking on a type would open a new tab that allows you
to explore that type on its own.
You can also use the "Filter" function at the bottom to limit
the display of types to a given type name.
Visualizing Changes
It is possible to examine which objects were created between
two snapshots in time. To do this, snapshot the application
twice, then set the checkbox on the snapshot that you want to
use as a reference, and then select the second snapshot.
The results displayed on the GUI will be only for the
Using the Command Line HeapShot
To use the command line version of HeapShot, you must first
get an object map. This can be done either with the GUI by
clicking on "Memory Snapshot" or you can send the PROF signal
to a Mono process that has been started with the
--profile=heap-shot command line option:
mono --profile=heap-shot MyProgram.exe
And on a separate window you type:
kill -PROF <pid-of-the-process>
Once you have the file, you can process it with:
heap-prof outfile_0.omap
The options are:
-i Show an inverse object dump
Show which objects hold references to a given
type, instead of which objects were created
by a given type.
-r Include roots
-s OLD Used to compare objects between two snapshots
in time.
Comparing changes across time
You must get two snapshots in time of your running
application, and then run the command like this:
heap-shot /tmp/outfile_1.omap -s /tmp/outfile_0.omap
This will only show the difference between the two times.
Creating a Mac app bundle
Just run "make mac-app"