From 63f3315e2b3eef38d47bf29bee647d13386ec448 Mon Sep 17 00:00:00 2001
From: Tor Egge <Tor.Egge@online.no>
Date: Sun, 28 Nov 2021 00:34:25 +0100
Subject: Avoid livelock when running sharded hash map unit test with valgrind.

---
 .../datastore/sharded_hash_map/sharded_hash_map_test.cpp  | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/vespalib/src/tests/datastore/sharded_hash_map/sharded_hash_map_test.cpp b/vespalib/src/tests/datastore/sharded_hash_map/sharded_hash_map_test.cpp
index 799f2c79dd4..3cd3d00645c 100644
--- a/vespalib/src/tests/datastore/sharded_hash_map/sharded_hash_map_test.cpp
+++ b/vespalib/src/tests/datastore/sharded_hash_map/sharded_hash_map_test.cpp
@@ -11,6 +11,7 @@
 #include <vespa/vespalib/gtest/gtest.h>
 
 #include <vespa/vespalib/datastore/unique_store_allocator.hpp>
+#include <thread>
 
 #include <vespa/log/log.h>
 LOG_SETUP("vespalib_datastore_shared_hash_test");
@@ -24,6 +25,18 @@ using MyHashMap = vespalib::datastore::ShardedHashMap;
 using GenerationHandler = vespalib::GenerationHandler;
 using vespalib::makeLambdaTask;
 
+namespace {
+
+void consider_yield(uint32_t i)
+{
+    if ((i % 1000) == 0) {
+        // Need to yield sometimes to avoid livelock when running unit test with valgrind
+        std::this_thread::yield();
+    }
+}
+
+}
+
 struct DataStoreShardedHashTest : public ::testing::Test
 {
     GenerationHandler _generationHandler;
@@ -142,6 +155,7 @@ DataStoreShardedHashTest::read_work(uint32_t cnt)
             EXPECT_EQ(key, wrapped_entry.value());
             ++found;
         }
+        consider_yield(i);
     }
     _done_read_work += i;
     _found_count += found;
@@ -168,6 +182,7 @@ DataStoreShardedHashTest::write_work(uint32_t cnt)
             remove(key);
         }
         commit();
+        consider_yield(i);
     }
     _done_write_work += cnt;
     _stop_read = 1;
-- 
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