frontend-grpc: limit the number of request processing threads

ReleaseNotes.md

@@ -7,6 +7,7 @@
 - cta/CTA#245 - Implements cta-admin functions in cta-frontend-grpc
 - cta/CTA#213 - Skip files with paths that have valid metadata
 - cta/CTA#321 - Add arguments to cta-change-storage-class to validate that the correct files are being changed
+- cta/CTA#318 - Limit the number of frontend-grpc request processing threads
 ### Bug Fixes
 - cta/CTA#305 - AllCatalogueSchema file not created when updating schema
 - cta/CTA#309 - Ignore 'NoSuchObject' exceptions thrown by non-existing objects during retrieve job requeuing

frontend-grpc/FrontendGRpcSvc.h

@@ -3,6 +3,7 @@
 
 #include "version.h"
 #include <grpcpp/grpcpp.h>
+#include <grpcpp/resource_quota.h>
 #include <grpcpp/security/server_credentials.h>
 
 #include <scheduler/Scheduler.hpp>
@@ -13,6 +14,7 @@ using cta::Scheduler;
 using cta::catalogue::Catalogue;
 using cta::frontend::rpc::CtaRpc;
 
+using grpc::ResourceQuota;
 using grpc::Server;
 using grpc::ServerBuilder;
 using grpc::ServerContext;

frontend-grpc/Main.cpp

@@ -44,7 +44,8 @@ std::string help =
     "\n"
     "where options can be:\n"
     "\n"
-    "\t--port <port>, -p <port>:\tTCP port number to use, defaults to 17017\n"
+    "\t--threads <N>, -c <N>    \tnumber of threads to process concurrent requests, defaults to 8x#CPUs\n"
+    "\t--port <port>, -p <port> \tTCP port number to use, defaults to 17017\n"
     "\t--log-header, -n         \tadd hostname and timestamp to log outputs, default\n"
     "\t--no-log-header, -s      \tdon't add hostname and timestamp to log outputs\n"
     "\t--tls, -t                \tenable Transport Layer Security (TLS)\n"
@@ -53,6 +54,7 @@ std::string help =
 
 static struct option long_options[] =
         {
+                {"threads", required_argument, 0, 'c'},
                 {"port", required_argument, 0, 'p'},
                 {"log-header", no_argument, 0, 'n'},
                 {"no-log-header", no_argument, 0, 's'},
@@ -88,8 +90,9 @@ int main(const int argc, char *const *const argv) {
     int option_index = 0;
     const std::string shortHostName = utils::getShortHostname();
     bool useTLS = false;
+    int threads = 8 * std::thread::hardware_concurrency();
 
-    while( (c = getopt_long(argc, argv, "p:nshv", long_options, &option_index)) != EOF) {
+    while( (c = getopt_long(argc, argv, "c:p:nshv", long_options, &option_index)) != EOF) {
 
         switch(c) {
             case 'p':
@@ -110,6 +113,9 @@ int main(const int argc, char *const *const argv) {
             case 't':
                 useTLS = true;
                 break;
+            case 'c':
+                threads = std::atoi(optarg);
+                break;
             default:
                 printHelpAndExit(1);
         }
@@ -192,6 +198,12 @@ int main(const int argc, char *const *const argv) {
     // Listen on the given address without any authentication mechanism.
     builder.AddListeningPort(server_address, creds);
 
+    // fixed the number of request threads
+    ResourceQuota quota;
+    quota.SetMaxThreads(threads);
+    lc.log(log::INFO, "Using " + std::to_string(threads) + " request processing threads");
+    builder.SetResourceQuota(quota);
+
     // Register "service" as the instance through which we'll communicate with
     // clients. In this case it corresponds to an *synchronous* service.
     builder.RegisterService(&svc);

frontend-grpc/cta-frontend-grpc.1cta

@@ -13,12 +13,12 @@
 .\"                 You should have received a copy of the GNU General Public License
 .\"                 along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
-.TH CTA-FRONTEND-GRPC "1cta" "2022-07-12" "CTA" "The CERN Tape Archive (CTA)"
+.TH CTA-FRONTEND-GRPC "1cta" "2023-03-07" "CTA" "The CERN Tape Archive (CTA)"
 .SH NAME
 cta-frontend-grpc \- gRPC-based Frontend for CTA
 
 .SH SYNOPSIS
-\fBcta-frontend-grpc\fP [--port \fIport\fR] [--log-header|--no-log-header] [--tls] [--version] [--help]
+\fBcta-frontend-grpc\fP [--port \fIport\fR] [--log-header|--no-log-header] [--tls] [--threads \fIN\fR] [--version] [--help]
 
 .SH DESCRIPTION
 \fBcta-frontend-grpc\fP is the daemon process providing gRPC endpoint for integration with storage systems.
@@ -28,6 +28,9 @@ cta-frontend-grpc \- gRPC-based Frontend for CTA
 \-p, \-\-port \fIport\fR
 TCP port used to accept connections from dCache.
 .TP
+\-c, \-\-threads \fIN\fR
+Maximal number of threads to process gRPC requests. The dafaults to 8x #CPUs.
+.TP
 \-n, \-\-log\-header
 Include timestamp and host name into the log messages.
 .TP