resource limit changes

- make the stack size limit a Nim define and use it in "config.nims" for
  the Windows C compiler flag and in "beacon_node.nim" for the POSIX
  runtime setting.
- warn when the open file limit is bellow 1024 (macOS, by default)
- increase the macOS open file limit in Travis
- add "-Wstack-usage=..." C compiler flag. No GCC warnings visible at the
  stack limit we set, but any would be visible by defining "cwarnings"
  in Nim.

.travis.yml

@@ -36,6 +36,7 @@ matrix:
     - os: osx
       before_install:
         - HOMEBREW_NO_AUTO_UPDATE=1 HOMEBREW_NO_INSTALL_CLEANUP=1 brew install ccache
+        - ulimit -n 1024 # increase the open files limit from the default of 512
       env:
         - NPROC=2
 

Makefile

@@ -80,6 +80,9 @@ ifneq ($(USE_LIBBACKTRACE), 0)
 deps: | libbacktrace
 endif
 
+# maximum stack size (in bytes) mirroring Android limits
+NIM_PARAMS := $(NIM_PARAMS) -d:stack_size=1000000
+
 #- deletes and recreates "beacon_chain.nims" which on Windows is a copy instead of a proper symlink
 update: | update-common
 	rm -f beacon_chain.nims && \

README.md

@@ -354,6 +354,12 @@ make -j$(nproc) NIMFLAGS="-d:release" USE_MULTITAIL=yes eth2_network_simulation
 make USE_LIBBACKTRACE=0 # expect the resulting binaries to be 2-3 times slower
 ```
 
+- show (some) C compiler warnings:
+
+```bash
+make NIMFLAGS="-d:cwarnings" beacon_node
+```
+
 ## License
 
 Licensed and distributed under either of

beacon_chain/beacon_node.nim

@@ -25,6 +25,9 @@ import
   sync_protocol, request_manager, validator_keygen, interop, statusbar,
   attestation_aggregation, sync_manager
 
+when defined(posix):
+  import posix
+
 const
   genesisFile = "genesis.ssz"
   hasPrompt = not defined(withoutPrompt)
@@ -1346,6 +1349,24 @@ programMain:
     quit(QuitFailure)
   setControlCHook(controlCHandler)
 
+  ## Set the stack size limit on POSIX systems (the Windows one is set in
+  ## config.nims).
+  # TODO: move this to nim-stew, if we need to use it elsewhere
+  when defined(posix):
+    const
+      RLIMIT_STACK = 3 # from "/usr/include/bits/resource.h"
+      stack_size {.intdefine.}: int = 0
+    var
+      rlimit: RLimit
+    when defined(stack_size):
+      if getrlimit(RLIMIT_STACK, rlimit) == -1:
+        error "getrlimit() error", msg = osErrorMsg(osLastError())
+      else:
+        rlimit.rlim_cur = stack_size
+        if setrlimit(RLIMIT_STACK, rlimit) == -1:
+          error "setrlimit() error", msg = osErrorMsg(osLastError())
+
+  ## handle command line arguments
   case config.cmd
   of createTestnet:
     var deposits: seq[Deposit]

config.nims

@@ -1,13 +1,22 @@
+import strutils
+
 if defined(release):
   switch("nimcache", "nimcache/release/$projectName")
 else:
   switch("nimcache", "nimcache/debug/$projectName")
 
+const stack_size {.intdefine.}: int = 0
+
+# conservative compile-time estimation for single functions
+when defined(stack_size) and defined(gcc):
+  switch("passC", "-Wstack-usage=" & $stack_size)
+
 if defined(windows):
   # disable timestamps in Windows PE headers - https://wiki.debian.org/ReproducibleBuilds/TimestampsInPEBinaries
   switch("passL", "-Wl,--no-insert-timestamp")
-  # increase stack size
-  switch("passL", "-Wl,--stack,1000000")
+  # set stack size
+  when defined(stack_size):
+    switch("passL", "-Wl,--stack," & $stack_size)
   # https://github.com/nim-lang/Nim/issues/4057
   --tlsEmulation:off
   if defined(i386):
@@ -43,9 +52,17 @@ else:
 
 switch("import", "testutils/moduletests")
 
-# the default open files limit is too low on macOS (512), breaking the
+# The default open files limit is too low on macOS (512), breaking the
 # "--debugger:native" build. It can be increased with `ulimit -n 1024`.
-if not defined(macosx):
+let openFilesLimitTarget = 1024
+var openFilesLimit = 0
+try:
+  openFilesLimit = staticExec("ulimit -n").parseInt()
+except:
+  echo "ulimit error"
+if openFilesLimit < openFilesLimitTarget:
+  echo "Open files limit too low. Increase it with \"ulimit -n " & $openFilesLimitTarget & "\""
+else:
   # add debugging symbols and original files and line numbers
   --debugger:native
   if not (defined(windows) and defined(i386)) and not defined(disable_libbacktrace):

nim.cfg

@@ -0,0 +1,9 @@
+# can't do this in "config.nims", probably due to parsing order
+@if cwarnings:
+  @if windows:
+    gcc.options.always = "-mno-ms-bitfields -Wno-all -Wno-discarded-qualifiers -Wno-incompatible-pointer-types"
+  @else:
+    gcc.options.always = "-Wno-all -Wno-discarded-qualifiers -Wno-incompatible-pointer-types"
+  @end
+@end
+