1 files changed, 32 insertions, 3 deletions

diff --git a/intern/cycles/device/opencl/opencl_util.cpp b/intern/cycles/device/opencl/opencl_util.cpp
index 978c75d2e2c..b8b07cf2947 100644
--- a/intern/cycles/device/opencl/opencl_util.cpp
+++ b/intern/cycles/device/opencl/opencl_util.cpp
@@ -23,6 +23,7 @@
 #  include "util/util_logging.h"
 #  include "util/util_md5.h"
 #  include "util/util_path.h"
+#  include "util/util_semaphore.h"
 #  include "util/util_system.h"
 #  include "util/util_time.h"
 
@@ -390,8 +391,27 @@ static void escape_python_string(string &str)
   string_replace(str, "'", "\'");
 }
 
+static int opencl_compile_process_limit()
+{
+  /* Limit number of concurrent processes compiling, with a heuristic based
+   * on total physical RAM and estimate of memory usage needed when compiling
+   * with all Cycles features enabled.
+   *
+   * This is somewhat arbitrary as we don't know the actual available RAM or
+   * how much the kernel compilation will needed depending on the features, but
+   * better than not limiting at all. */
+  static const int64_t GB = 1024LL * 1024LL * 1024LL;
+  static const int64_t process_memory = 2 * GB;
+  static const int64_t base_memory = 2 * GB;
+  static const int64_t system_memory = system_physical_ram();
+  static const int64_t process_limit = (system_memory - base_memory) / process_memory;
+
+  return max((int)process_limit, 1);
+}
+
 bool OpenCLDevice::OpenCLProgram::compile_separate(const string &clbin)
 {
+  /* Construct arguments. */
   vector<string> args;
   args.push_back("--background");
   args.push_back("--factory-startup");
@@ -419,14 +439,23 @@ bool OpenCLDevice::OpenCLProgram::compile_separate(const string &clbin)
       kernel_file_escaped.c_str(),
       clbin_escaped.c_str()));
 
-  double starttime = time_dt();
+  /* Limit number of concurrent processes compiling. */
+  static thread_counting_semaphore semaphore(opencl_compile_process_limit());
+  semaphore.acquire();
+
+  /* Compile. */
+  const double starttime = time_dt();
   add_log(string("Cycles: compiling OpenCL program ") + program_name + "...", false);
   add_log(string("Build flags: ") + kernel_build_options, true);
-  if (!system_call_self(args) || !path_exists(clbin)) {
+  const bool success = system_call_self(args);
+  const double elapsed = time_dt() - starttime;
+
+  semaphore.release();
+
+  if (!success || !path_exists(clbin)) {
     return false;
   }
 
-  double elapsed = time_dt() - starttime;
   add_log(
       string_printf("Kernel compilation of %s finished in %.2lfs.", program_name.c_str(), elapsed),
       false);