[DynInst_API:] attaching to multiple processes

[Marc Brünink <marc@xxxxxxxxxx>]

Hi,

I have 2 processes, A and B.
I can attach to Process A, load a library using 
BPatch_addressSpace::loadLibrary and continue the execution. Same thing 
for process B.
However, I cannot do this in sequence. This fails:

1. attach to A
2. load the lib into A
3. continue A
4. attach to B
5. load the lib into B
6. continue B

The second load will hang. However, if I do not continue the execution 
of process A, it seems to work.
1. attach to A
2. load the lib into A
3. attach to B
4. load the lib into B
5. continue A and B


My 2 questions are:
1. Should the first scenario work as well?
2. What are best practices if I attach to multiple processes? Is it safe 
to have one process running while stopping and manipulating another one? 
Or should I expect trouble due to internal issues, e.g. event handling?

Marc



#0  0x00007f491b30ed84 in pthread_cond_wait@@GLIBC_2.3.2 () from 
/lib/x86_64-linux-gnu/libpthread.so.0
#1  0x00007f490c7ec07d in CondVar::wait (this=<optimized out>) at 
../../common/src/dthread-unix.C:180
#2  0x00007f490c80c766 in MailboxMT::dequeue (this=0x7f49040008c0, 
block=true) at ../src/mailbox.C:156
#3  0x00007f490c831995 in int_process::waitAndHandleEvents (block=true) 
at ../src/process.C:1015
#4  0x00007f490c832a84 in Dyninst::ProcControlAPI::Process::runIRPCSync 
(this=<optimized out>, irpc=...)
    at ../src/process.C:6601
#5  0x00007f490d1ad2d9 in PCProcess::postIRPC_internal (this=0x7853d30, 
buf=0x8740f00, size=157, breakOffset=155,
    resultReg=0, addr=<optimized out>, userData=0x78a01d0, 
runProcessWhenDone=false, thread=0x0, synchronous=true,
    userRPC=true, isMemAlloc=false, result=0x0) at 
../../dyninstAPI/src/dynProcess.C:2177
#6  0x00007f490d1ad823 in PCProcess::postIRPC (this=0x7853d30, 
action=..., userData=0x78a01d0, runProcessWhenDone=false,
    thread=0x0, synchronous=true, result=0x0, userRPC=true, 
isMemAlloc=false, addr=0)
    at ../../dyninstAPI/src/dynProcess.C:2061
#7  0x00007f490d0fe3c5 in BPatch_process::oneTimeCodeInternal 
(this=0x8740e70, expr=..., thread=<optimized out>,
    userData=0x0, cb=<optimized out>, synchronous=true, err=0x0, 
userRPC=true) at ../../dyninstAPI/src/BPatch_process.C:956
#8  0x00007f490d100d1a in BPatch_process::loadLibrary (this=0x8740e70,
    libname=0x7f490d49efb8 "/my/super/path/callbacks.so")
    at ../../dyninstAPI/src/BPatch_process.C:1050