add ability to limit concurrency (#565)

effective concurrency in zenserver can be limited via the `--corelimit=<N>` option on the command line. Any value passed in here will be used instead of the return value from `std::thread::hardware_concurrency()` if it is lower.

* added --corelimit option to zenserver
* made sure thread pools are configured lazily and not during global init
* added log output indicating effective and HW concurrency
* added change log entry
* removed debug logging from ZenEntryPoint::Run()

also removed main thread naming on Linux since it makes the output from `top` and similar tools confusing (it shows `main` instead of `zenserver`)

1 files changed, 3 insertions, 3 deletions

diff --git a/src/zenstore/compactcas.cpp b/src/zenstore/compactcas.cpp
index 5cc4dad54..bf843171e 100644
--- a/src/zenstore/compactcas.cpp
+++ b/src/zenstore/compactcas.cpp
@@ -1722,7 +1722,7 @@ TEST_CASE("compactcas.restart")
 {
 	uint64_t ExpectedSize = 0;
 
-	WorkerThreadPool ThreadPool(Max(std::thread::hardware_concurrency() - 1u, 2u), "put");
+	WorkerThreadPool ThreadPool(Max(GetHardwareConcurrency() - 1u, 2u), "put");
 
 	auto GenerateChunks = [&](CasContainerStrategy& Cas, size_t ChunkCount, uint64_t ChunkSize, std::vector<IoHash>& Hashes) {
 		Latch								   WorkLatch(1);
@@ -1959,7 +1959,7 @@ TEST_CASE("compactcas.restart")
 TEST_CASE("compactcas.iteratechunks")
 {
 	std::atomic<size_t> WorkCompleted = 0;
-	WorkerThreadPool	ThreadPool(Max(std::thread::hardware_concurrency() - 1u, 2u), "put");
+	WorkerThreadPool	ThreadPool(Max(GetHardwareConcurrency() - 1u, 2u), "put");
 
 	const uint64_t kChunkSize  = 1048 + 395;
 	const size_t   kChunkCount = 63840;
@@ -2035,7 +2035,7 @@ TEST_CASE("compactcas.iteratechunks")
 			WorkLatch.Wait();
 		}
 
-		WorkerThreadPool BatchWorkerPool(Max(std::thread::hardware_concurrency() - 1u, 2u), "fetch");
+		WorkerThreadPool BatchWorkerPool(Max(GetHardwareConcurrency() - 1u, 2u), "fetch");
 		{
 			std::vector<std::atomic<bool>> FetchedFlags(Hashes.size());
 			std::atomic<uint64_t>		   FetchedSize = 0;