Trace object allocation flag proposal

[Xiaobin Lu]

Hi folks,

I would like to propose a way to trace object allocation on Linux. On
Solaris, we have DTrace which is pretty nice. But on Linux, it is almost
impossible to do so. Correct me if I am wrong here.

So I am thinking to add a manageable VM flag and let's call it
TraceObjectAllocation. When enabled, we can output something like:

thread id: 10     class name: java/lang/reflect/Method             size: 80
bytes
thread id: 10     class name: [Ljava/lang/Class;                    size: 16
bytes
thread id: 10     class name: [C
                         size: 56 bytes
thread id: 10     class name: java/lang/reflect/Method            size: 80
bytes
thread id: 10     class name: [Ljava/lang/Class;                   size: 16
bytes

As you could imagine, this could be very useful to keep track of object
allocation behavior in the app. Some smart tool can take advantage of this
to print a histogram (like top 10 hot allocations) of object allocation. I
would like to know your thoughts and suggestions on this.

I have a detailed proposal on this attached in PDF file.

Thanks,

-Xiaobin
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