ydb/contrib/libs/grpc/patches/29-set-nexting-thread-num-via-env.patch

--- contrib/libs/grpc/src/cpp/common/completion_queue_cc.cc	(index)
+++ contrib/libs/grpc/src/cpp/common/completion_queue_cc.cc	(working tree)
@@ -31,10 +31,23 @@
 #include "src/core/lib/gpr/useful.h"
 #include "src/core/lib/gprpp/sync.h"
 #include "src/core/lib/gprpp/thd.h"
+#include "src/core/lib/gprpp/env.h"
+#include "src/core/lib/gpr/string.h"
 
 namespace grpc {
 namespace {
 
+size_t GetNextingThreadNumFromEnv() {
+  auto value = grpc_core::GetEnv("GRPC_NEXTING_THREAD_NUM_ENV");
+  if (!value.has_value()) return 0;
+  int parse_succeeded = gpr_parse_nonnegative_int(value->c_str());
+
+  if (parse_succeeded <= 0) {
+      return 0;
+  }
+  return static_cast<size_t>(parse_succeeded);
+}
+
 gpr_once g_once_init_callback_alternative = GPR_ONCE_INIT;
 grpc_core::Mutex* g_callback_alternative_mu;
 
@@ -55,6 +68,13 @@ struct CallbackAlternativeCQ {
       cq = new CompletionQueue;
       int num_nexting_threads =
           grpc_core::Clamp(gpr_cpu_num_cores() / 2, 2u, 16u);
+
+      auto threads_limit_env = GetNextingThreadNumFromEnv();
+      if (threads_limit_env) {
+        gpr_log(GPR_INFO, "Nexting thread number changed via env from %d to %zd", num_nexting_threads, threads_limit_env);
+        num_nexting_threads = static_cast<int>(threads_limit_env);
+      }
+
       nexting_threads = new std::vector<grpc_core::Thread>;
       for (int i = 0; i < num_nexting_threads; i++) {
         nexting_threads->emplace_back(