From 138ed373b04773bee8baa78f0e68feff5ff6aaed Mon Sep 17 00:00:00 2001
From: Marcus Holland-Moritz <github@mhxnet.de>
Date: Tue, 19 Dec 2023 19:58:42 +0100
Subject: [PATCH] refactor(worker_group): use hardware concurrency when
 num_workers == 0

---
 src/dwarfs/worker_group.cpp | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/dwarfs/worker_group.cpp b/src/dwarfs/worker_group.cpp
index bcf0c5d7..589af68a 100644
--- a/src/dwarfs/worker_group.cpp
+++ b/src/dwarfs/worker_group.cpp
@@ -35,6 +35,7 @@
 #include <folly/String.h>
 #include <folly/portability/PThread.h>
 #include <folly/portability/Windows.h>
+#include <folly/system/HardwareConcurrency.h>
 #include <folly/system/ThreadName.h>
 
 #include "dwarfs/error.h"
@@ -102,7 +103,7 @@ class basic_worker_group final : public worker_group::impl, private Policy {
       , pending_(0)
       , max_queue_len_(max_queue_len) {
     if (num_workers < 1) {
-      DWARFS_THROW(runtime_error, "invalid number of worker threads");
+      num_workers = std::max(folly::hardware_concurrency(), 1u);
     }
 
     if (!group_name) {