From 2979229696cb83eef925a34cedcf56856f69b080 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?J=C3=BCrg=20Billeter?= <j@bitron.ch>
Date: Tue, 2 Jun 2020 07:46:45 +0200
Subject: _platform: Drop maximize_open_file_limit()

Without the SafeHardlinks FUSE filesystem there is no longer a need to
increase the open file limit.
---
 src/buildstream/_platform/darwin.py   | 24 ------------------------
 src/buildstream/_platform/platform.py | 17 -----------------
 src/buildstream/_platform/win32.py    | 23 -----------------------
 3 files changed, 64 deletions(-)

(limited to 'src/buildstream')

diff --git a/src/buildstream/_platform/darwin.py b/src/buildstream/_platform/darwin.py
index fc9be342f..00bca2c4c 100644
--- a/src/buildstream/_platform/darwin.py
+++ b/src/buildstream/_platform/darwin.py
@@ -15,36 +15,12 @@
 #  You should have received a copy of the GNU Lesser General Public
 #  License along with this library. If not, see <http://www.gnu.org/licenses/>.
 
-import resource
-
 from ..sandbox import SandboxDummy
 
 from .platform import Platform
 
 
 class Darwin(Platform):
-
-    # This value comes from OPEN_MAX in syslimits.h
-    OPEN_MAX = 10240
-
-    def maximize_open_file_limit(self):
-        # Note that on Mac OSX, you may not be able to simply set the soft
-        # limit to the reported hard limit, as it may not be the only limit in
-        # effect. The output of these commands may be somewhat independent:
-        #
-        #   $ launchctl limit
-        #   $ sysctl -a | grep files
-        #
-        # The OPEN_MAX value from syslimits.h seems to be fairly safe, although
-        # users may tweak their individual systems to have different values.
-        # Without a way to determine what the real limit is, we risk failing to
-        # increase the limit. Perhaps the complication is why psutil does not
-        # support rlimit on Mac.
-        #
-        old_soft_limit, hard_limit = resource.getrlimit(resource.RLIMIT_NOFILE)
-        soft_limit = min(max(self.OPEN_MAX, old_soft_limit), hard_limit)
-        resource.setrlimit(resource.RLIMIT_NOFILE, (soft_limit, hard_limit))
-
     @staticmethod
     def _check_dummy_sandbox_config(config):
         pass
diff --git a/src/buildstream/_platform/platform.py b/src/buildstream/_platform/platform.py
index d0debfc7b..84d1fb231 100644
--- a/src/buildstream/_platform/platform.py
+++ b/src/buildstream/_platform/platform.py
@@ -39,7 +39,6 @@ class Platform:
     #     force_sandbox (bool): Force bst to use a particular sandbox
     #
     def __init__(self, force_sandbox=None):
-        self.maximize_open_file_limit()
         self._local_sandbox = None
         self.dummy_reasons = []
         self._setup_sandbox(force_sandbox)
@@ -248,22 +247,6 @@ class Platform:
             "Platform {platform} does not implement check_sandbox_config()".format(platform=type(self).__name__)
         )
 
-    def maximize_open_file_limit(self):
-        # Need to set resources for _frontend/app.py as this is dependent on the platform
-        # SafeHardlinks FUSE needs to hold file descriptors for all processes in the sandbox.
-        # Avoid hitting the limit too quickly, by increasing it as far as we can.
-
-        # Import this late, as it is not available on Windows. Note that we
-        # could use `psutil.Process().rlimit` instead, but this would introduce
-        # a dependency on the `prlimit(2)` call, which seems to only be
-        # available on Linux. For more info:
-        # https://github.com/giampaolo/psutil/blob/cbf2bafbd33ad21ef63400d94cb313c299e78a45/psutil/_psutil_linux.c#L45
-        import resource
-
-        soft_limit, hard_limit = resource.getrlimit(resource.RLIMIT_NOFILE)
-        if soft_limit != hard_limit:
-            resource.setrlimit(resource.RLIMIT_NOFILE, (hard_limit, hard_limit))
-
     def _setup_dummy_sandbox(self):
         raise ImplError(
             "Platform {platform} does not implement _setup_dummy_sandbox()".format(platform=type(self).__name__)
diff --git a/src/buildstream/_platform/win32.py b/src/buildstream/_platform/win32.py
index 33645e030..5045c9e3e 100644
--- a/src/buildstream/_platform/win32.py
+++ b/src/buildstream/_platform/win32.py
@@ -20,29 +20,6 @@ from .platform import Platform
 
 
 class Win32(Platform):
-    def maximize_open_file_limit(self):
-        # Note that on Windows, we don't have the 'resource' module to help us
-        # configure open file limits.
-        #
-        # 'psutil' provides an rlimit implementation that is only available on
-        # Linux, as of version 5.3.
-        #
-        # Given that this limit is only important for SafeHardLinks FUSE, and
-        # we don't have FUSE on Windows, this won't be an obstacle for now.
-        #
-        # If it does turn out to be an obstacle, beware that the Windows API
-        # `_setmaxstdio` for increasing the open file limit only applies to the
-        # 'stream I/O level', i.e. `fopen()` and friends. CPython opens files
-        # using `_wopen()`, which is at the 'low I/O level'.
-        #
-        # You can see this in the function `os_open_impl` in `posixmodule.c` in
-        # CPython version 3.9.
-        #
-        # For more information:
-        # https://docs.microsoft.com/en-us/cpp/c-runtime-library/reference/setmaxstdio
-        #
-        pass
-
     @staticmethod
     def _check_dummy_sandbox_config(config):
         pass
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