Make gcmole execute in parallel.

tools/gcmole/gcmole.lua

 -- Copyright 2011 the V8 project authors. All rights reserved.
 -- Redistribution and use in source and binary forms, with or without
 -- modification, are permitted provided that the following conditions are
 -- met:
 --
 --     * Redistributions of source code must retain the above copyright
 --       notice, this list of conditions and the following disclaimer.
 --     * Redistributions in binary form must reproduce the above
 --       copyright notice, this list of conditions and the following
 --       disclaimer in the documentation and/or other materials provided
@@ skipping 16 matching lines @@
 
 -- This is main driver for gcmole tool. See README for more details.
 -- Usage: CLANG_BIN=clang-bin-dir lua tools/gcmole/gcmole.lua [arm|ia32|x64]
 
 local DIR = arg[0]:match("^(.+)/[^/]+$")
 
 local FLAGS = {
    -- Do not build gcsuspects file and reuse previously generated one.
    reuse_gcsuspects = false;
 
+   -- Don't use parallel python runner.
+   sequential = false;
+
    -- Print commands to console before executing them.
    verbose = false;
 
    -- Perform dead variable analysis (generates many false positives).
    -- TODO add some sort of whiteliste to filter out false positives.
    dead_vars = false;
 
    -- When building gcsuspects whitelist certain functions as if they
    -- can be causing GC. Currently used to reduce number of false
    -- positives in dead variables analysis. See TODO for WHITELIST
@@ skipping 59 matching lines @@
       .. " -Xclang -triple -Xclang " .. triple
       .. " -D" .. arch_define
       .. " -DENABLE_DEBUGGER_SUPPORT"
       .. " -DV8_I18N_SUPPORT"
       .. " -I./"
       .. " -Ithird_party/icu/source/common"
       .. " -Ithird_party/icu/source/i18n"
       .. " " .. arch_options
 end
 
+local function IterTable(t)
+  return coroutine.wrap(function ()
+    for i, v in ipairs(t) do
+      coroutine.yield(v)
+    end
+  end)
+end
+
+local function SplitResults(lines, func)
+   -- Splits the output of parallel.py and calls func on each result.
+   -- Bails out in case of an error in one of the executions.
+   local current = {}
+   local filename = ""
+   for line in lines do
+      local new_file = line:match "^______________ (.*)$"
+      local code = line:match "^______________ finish (%d+) ______________$"
+      if code then
+         if tonumber(code) > 0 then
+            log(table.concat(current, "\n"))
+            log("Failed to examine " .. filename)
+            return false
+         end
+         log("-- %s", filename)
+         func(filename, IterTable(current))
+      elseif new_file then
+         filename = new_file
+         current = {}
+      else
+         table.insert(current, line)
+      end
+   end
+   return true
+end
+
 function InvokeClangPluginForEachFile(filenames, cfg, func)
    local cmd_line = MakeClangCommandLine(cfg.plugin,
                                          cfg.plugin_args,
                                          cfg.triple,
                                          cfg.arch_define,
                                          cfg.arch_options)
-   for _, filename in ipairs(filenames) do
-      log("-- %s", filename)
-      local action = cmd_line .. " " .. filename .. " 2>&1"
+   if FLAGS.sequential then
+      log("** Sequential execution.")
+      for _, filename in ipairs(filenames) do
+         log("-- %s", filename)
+         local action = cmd_line .. " " .. filename .. " 2>&1"
+         if FLAGS.verbose then print('popen ', action) end
+         local pipe = io.popen(action)
+         func(filename, pipe:lines())
+         local success = pipe:close()
+         if not success then error("Failed to run: " .. action) end
+      end
+   else
+      log("** Parallel execution.")
+      local action = "python tools/gcmole/parallel.py \""
+         .. cmd_line .. "\" " .. table.concat(filenames, " ")
       if FLAGS.verbose then print('popen ', action) end
       local pipe = io.popen(action)
-      func(filename, pipe:lines())
-      local success = pipe:close()
-      if not success then error("Failed to run: " .. action) end
+      local success = SplitResults(pipe:lines(), func)
+      local closed = pipe:close()
+      if not (success and closed) then error("Failed to run: " .. action) end
    end
 end
 
 -------------------------------------------------------------------------------
 -- GYP file parsing
 
 local function ParseGYPFile()
    local gyp = ""
    local gyp_files = { "tools/gyp/v8.gyp", "test/cctest/cctest.gyp" }
    for i = 1, #gyp_files do
@@ skipping 253 matching lines @@
 
 for _, arch in ipairs(ARCHS) do
    if not ARCHITECTURES[arch] then
       error ("Unknown arch: " .. arch)
    end
 
    errors = SafeCheckCorrectnessForArch(arch, report) or errors
 end
 
 os.exit(errors and 1 or 0)