[Lldb-commits] [PATCH] D93895: Implement vAttachWait in lldb-server

Mon Jan 4 15:39:05 PST 2021

augusto2112 added inline comments.

================
Comment at: lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationServerLLGS.cpp:344
+  // TODO: Make the polling interval configurable.
+  std::chrono::milliseconds polling_interval = std::chrono::seconds(1);
+
----------------
clayborg wrote:
> We probably want this to be quite a bit shorter than 1 second. Why? Because if you don't find the process right away, 1 second is a long time for the system to wait and your program can execute quite a few instructions in 1 second. By the time you attach, you might have missed your breakpoint at main. Nothing will guarantee hitting a breakpoint, but I would suggest making a smaller timeout, maybe like 1 millisecond. It would be good to benchmark this a bit by waiting for a process and not launching a new process to see how much CPU lldb-server takes up with a shorter timeout.
> 
> Adding a command line option might be nice is someone could specify "--wait-poll-msec 0" to constantly poll the system as fast as possible in case they do need to catch the process as early as possible.
> Adding a command line option might be nice is someone could specify "--wait-poll-msec 0" to constantly poll the system as fast as possible in case they do need to catch the process as early as possible.

It looks like there already is an option like what you're describing on debugserver: "waitfor-interval". As well as another related flag: "waitfor-duration".

I'll try implementing them in this patch as well.

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D93895/new/

https://reviews.llvm.org/D93895