http2: shrink default `vector::reserve()` allocations

Allocating memory upfront comes with overhead, and in particular, `std::vector` implementations do not necessarily return memory to the system when one might expect that (e.g. after shrinking the vector). Backport-PR-URL: #29123 PR-URL: #29122 Reviewed-By: Rich Trott <rtrott@gmail.com> Reviewed-By: James M Snell <jasnell@gmail.com>
nodejs · Aug 10, 2019 · 460f896c631f1be52b0ab6c9f30e0b66f601b2a1 · 460f896
1 parent f4242e2
commit 460f896c631f1be52b0ab6c9f30e0b66f601b2a1
Unified Split

Showing with 2 additions and 2 deletions.

+2 −2 src/node_http2.cc
diff --git a/src/node_http2.cc b/src/node_http2.cc
@@ -632,7 +632,7 @@ Http2Session::Http2Session(Environment* env,
  // fails.
  CHECK_EQ(fn(&session_, callbacks, this, *opts, *allocator_info), 0);
-  
-  outgoing_storage_.reserve(4096);
+  
+  outgoing_storage_.reserve(1024);
  outgoing_buffers_.reserve(32);
  {
@@ -1947,7 +1947,7 @@ Http2Stream::Http2Stream(Http2Session* session,
  if (max_header_pairs_ == 0) {
    max_header_pairs_ = DEFAULT_MAX_HEADER_LIST_PAIRS;
  }
-  
-  current_headers_.reserve(max_header_pairs_);
+  
+  current_headers_.reserve(std::min(max_header_pairs_, 12u));
  // Limit the number of header octets
  max_header_length_ =