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: #29124 PR-URL: #29122 Reviewed-By: Rich Trott <[email protected]> Reviewed-By: James M Snell <[email protected]>
nodejs · Aug 15, 2019 · 156f2f3 · 156f2f3
1 parent 10f05b6
commit 156f2f3
Showing 1 changed file with 5 additions and 4 deletions.
diff --git a/src/node_http2.cc b/src/node_http2.cc
@@ -668,7 +668,7 @@ 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);
 
   {
@@ -1993,9 +1993,10 @@ Http2Stream::Http2Stream(
 
   // Limit the number of header pairs
   max_header_pairs_ = session->GetMaxHeaderPairs();
-  if (max_header_pairs_ == 0)
-  max_header_pairs_ = DEFAULT_MAX_HEADER_LIST_PAIRS;
-  current_headers_.reserve(max_header_pairs_);
+  if (max_header_pairs_ == 0) {
+    max_header_pairs_ = DEFAULT_MAX_HEADER_LIST_PAIRS;
+  }
+  current_headers_.reserve(std::min(max_header_pairs_, 12u));
 
   // Limit the number of header octets
   max_header_length_ =