src: override v8 thread defaults using cli options
Based on the conversation in #4243 this implements a way to increase
and decrease the size of the thread pool used in v8.
Currently v8 restricts the thread pool size to `kMaxThreadPoolSize`
which at this commit is (4). So it is only possible to
decrease the thread pool size at the time of this commit. However with
changes upstream this could change at a later date.
If set to 0 then v8 would choose an appropriate size of the thread pool
based on the number of online processors.
PR-URL: https://github.com/nodejs/node/pull/4344
Reviewed-By: James M Snell <[email protected]>
Reviewed-By: Fedor Indutny <[email protected]>
Reviewed-By: Colin Ihrig <[email protected]>
diff --git a/doc/node.1 b/doc/node.1
index 05ecfc4..7785ef4 100644
--- a/doc/node.1
+++ b/doc/node.1
@@ -100,6 +100,13 @@
Print v8 command line options.
.TP
+.BR \-\-v8\-pool\-size =\fInum\fR
+Set v8's thread pool size which will be used to allocate background jobs.
+If set to 0 then v8 will choose an appropriate size of the thread pool based
+on the number of online processors. If the value provided is larger than v8's
+max then the largest value will be chosen.
+
+.TP
.BR \-\-tls\-cipher\-list =\fIlist\fR
Specify an alternative default TLS cipher list. (Requires Node.js to be built with crypto support. (Default))
@@ -115,7 +122,6 @@
.BR \-\-icu\-data\-dir =\fIfile\fR
Specify ICU data load path. (overrides \fBNODE_ICU_DATA\fR)
-
.SH ENVIRONMENT VARIABLES
.TP
diff --git a/src/node.cc b/src/node.cc
index af9cd1a..f9a0519 100644
--- a/src/node.cc
+++ b/src/node.cc
@@ -148,6 +148,8 @@
static bool use_debug_agent = false;
static bool debug_wait_connect = false;
static int debug_port = 5858;
+static const int v8_default_thread_pool_size = 4;
+static int v8_thread_pool_size = v8_default_thread_pool_size;
static bool prof_process = false;
static bool v8_is_profiling = false;
static bool node_is_initialized = false;
@@ -178,7 +180,6 @@
static node::atomic<Isolate*> node_isolate;
static v8::Platform* default_platform;
-
static void PrintErrorString(const char* format, ...) {
va_list ap;
va_start(ap, format);
@@ -3319,6 +3320,7 @@
" --zero-fill-buffers automatically zero-fill all newly allocated\n"
" Buffer and SlowBuffer instances\n"
" --v8-options print v8 command line options\n"
+ " --v8-pool-size=num set v8's thread pool size\n"
#if HAVE_OPENSSL
" --tls-cipher-list=val use an alternative default TLS cipher list\n"
#if NODE_FIPS_MODE
@@ -3466,6 +3468,8 @@
} else if (strcmp(arg, "--v8-options") == 0) {
new_v8_argv[new_v8_argc] = "--help";
new_v8_argc += 1;
+ } else if (strncmp(arg, "--v8-pool-size=", 15) == 0) {
+ v8_thread_pool_size = atoi(arg + 15);
#if HAVE_OPENSSL
} else if (strncmp(arg, "--tls-cipher-list=", 18) == 0) {
default_cipher_list = arg + 18;
@@ -4285,8 +4289,7 @@
V8::SetEntropySource(crypto::EntropySource);
#endif
- const int thread_pool_size = 4;
- default_platform = v8::platform::CreateDefaultPlatform(thread_pool_size);
+ default_platform = v8::platform::CreateDefaultPlatform(v8_thread_pool_size);
V8::InitializePlatform(default_platform);
V8::Initialize();
