Cygwin: tls_pathbuf: Use Windows heap

Rather than using malloc/free for the buffers, we're now using
HeapAlloc/HeapFree on a HEAP_NO_SERIALIZE heap created for this
thread.

Advantages:
- Less contention. Our malloc/free doesn't scale well in
  multithreaded scenarios
- Even faster heap allocation by using a non serialized heap.
- Internal, local, temporary data not cluttering the user heap.
- Internal, local, temporary data not copied over to child process
  at fork().

Disadvantage:
- A forked process has to start allocating temporary buffers from
  scratch.  However, this should be alleviated by the fact that
  buffer allocation usually reaches its peak very early in process
  runtime, so the longer the proceess runs, the less buffers have
  to allocated, and, only few processes don't exec after fork
  anyway.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>

1 files changed, 2 insertions, 0 deletions

diff --git a/winsup/cygwin/cygtls.cc b/winsup/cygwin/cygtls.cc
index cf3a7daba..afaee8e97 100644
--- a/winsup/cygwin/cygtls.cc
+++ b/winsup/cygwin/cygtls.cc
@@ -64,6 +64,7 @@ _cygtls::init_thread (void *x, DWORD (*func) (void *, void *))
   initialized = CYGTLS_INITIALIZED;
   errno_addr = &(local_clib._errno);
   locals.cw_timer = NULL;
+  locals.pathbufs.clear ();
 
   if ((void *) func == (void *) cygthread::stub
       || (void *) func == (void *) cygthread::simplestub)
@@ -84,6 +85,7 @@ _cygtls::fixup_after_fork ()
   signal_arrived = NULL;
   locals.select.sockevt = NULL;
   locals.cw_timer = NULL;
+  locals.pathbufs.clear ();
   wq.thread_ev = NULL;
 }