Linux (and Android): Implement GetDefaultConcurrentLinks() for Linux Builds

pylib/gyp/generator/ninja.py

 # Copyright (c) 2013 Google Inc. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import copy
 import hashlib
 import multiprocessing
 import os.path
 import re
 import signal
@@ skipping 1465 matching lines @@
         ("ullTotalVirtual", ctypes.c_ulonglong),
         ("ullAvailVirtual", ctypes.c_ulonglong),
         ("sullAvailExtendedVirtual", ctypes.c_ulonglong),
       ]
 
     stat = MEMORYSTATUSEX()
     stat.dwLength = ctypes.sizeof(stat)
     ctypes.windll.kernel32.GlobalMemoryStatusEx(ctypes.byref(stat))
 
     return max(1, stat.ullTotalPhys / (4 * (2 ** 30)))  # total / 4GB
+  elif sys.platform.startswith('linux'):
+    with open("/proc/meminfo") as meminfo:
+      memtotal_re = re.compile(r'^MemTotal:\s*(\d*)\s*kB')
+      for line in meminfo:
+        match = memtotal_re.match(line)
+        if not match:
+          continue
+        # Allow 8Gb per link on Linux because Gold is quite memory hungry
+        return max(1, int(match.group(1)) / (8 * (2 ** 20)))

[Nico, 2013/08/27 22:01:04]

Isn't 2**20 a megabyte, not a gigabyte?

...ah, /proc/meminfo stores kB, not bytes. This isn't super clear, maybe

  available_memory_bytes = int(match.group(1)) * 1024
  return max(1, available_memory_bytes / (8 * (2 ** 30)))

would be a bit clearer?

+    return 1
   else:
     # TODO(scottmg): Implement this for other platforms.
     return 1
 
 
 def _GetWinLinkRuleNameSuffix(embed_manifest, link_incremental):
   """Returns the suffix used to select an appropriate linking rule depending on
   whether the manifest embedding and/or incremental linking is enabled."""
   suffix = ''
   if embed_manifest:
@@ skipping 547 matching lines @@
           arglists.append(
               (target_list, target_dicts, data, params, config_name))
         pool.map(CallGenerateOutputForConfig, arglists)
       except KeyboardInterrupt, e:
         pool.terminate()
         raise e
     else:
       for config_name in config_names:
         GenerateOutputForConfig(target_list, target_dicts, data, params,
                                 config_name)