vim-patch:8.1.1007: using closure may consume a lot of memory

Problem:    Using closure may consume a lot of memory.
Solution:   unreference items that are no longer needed. Add a test. (Ozaki
            Kiichi, closes vim/vim#3961)
https://github.com/vim/vim/commit/209b8e3e3bf7a4a3d102134124120f6c7f57d560

1 files changed, 151 insertions, 0 deletions

diff --git a/test/functional/legacy/memory_usage_spec.lua b/test/functional/legacy/memory_usage_spec.lua
new file mode 100644
index 0000000000..14a7f2dbdd
--- /dev/null
+++ b/test/functional/legacy/memory_usage_spec.lua
@@ -0,0 +1,151 @@
+local helpers = require('test.functional.helpers')(after_each)
+local clear = helpers.clear
+local eval = helpers.eval
+local eq = helpers.eq
+local feed_command = helpers.feed_command
+local iswin = helpers.iswin
+local retry = helpers.retry
+local ok = helpers.ok
+local source = helpers.source
+
+local monitor_memory_usage = {
+  memory_usage = function(self)
+    local handle
+    if iswin() then
+      handle = io.popen('wmic process where processid=' ..self.pid..' get WorkingSetSize')
+    else
+      handle = io.popen('ps -o rss= -p '..self.pid)
+    end
+    return tonumber(handle:read('*a'):match('%d+'))
+  end,
+  op = function(self)
+    retry(nil, 10000, function()
+      local val = self.memory_usage(self)
+      if self.min > val then
+        self.min = val
+      elseif self.max < val then
+        self.max = val
+      end
+      table.insert(self.hist, val)
+      ok(#self.hist > 20)
+      local result = {}
+      for key,value in ipairs(self.hist) do
+        if value ~= self.hist[key + 1] then
+          table.insert(result, value)
+        end
+      end
+      table.remove(self.hist, 1)
+      self.last = self.hist[#self.hist]
+      eq(#result, 1)
+    end)
+  end,
+  dump = function(self)
+    return 'max: '..self.max ..', last: '..self.last
+  end,
+  monitor_memory_usage = function(self, pid)
+    local obj = {
+      pid = pid,
+      min = 0,
+      max = 0,
+      last = 0,
+      hist = {},
+    }
+    setmetatable(obj, { __index = self })
+    obj:op()
+    return obj
+  end
+}
+setmetatable(monitor_memory_usage,
+{__call = function(self, pid)
+  return monitor_memory_usage.monitor_memory_usage(self, pid)
+end})
+
+describe('memory usage', function()
+  local function check_result(tbl, status, result)
+    if not status then
+      print('')
+      for key, val in pairs(tbl) do
+        print(key, val:dump())
+      end
+      error(result)
+    end
+  end
+
+  local function isasan()
+    local version = eval('execute("version")')
+    return version:match('-fsanitize=[a-z,]*address')
+  end
+
+  before_each(clear)
+
+  --[[
+  Case: if a local variable captures a:000, funccall object will be free
+  just after it finishes.
+  ]]--
+  it('function capture vargs', function()
+    if isasan() then
+      pending('ASAN build is difficult to estimate memory usage')
+    end
+    if iswin() and eval("executable('wmic')")  == 0 then
+      pending('missing "wmic" command')
+    elseif eval("executable('ps')")  == 0 then
+      pending('missing "ps" command')
+    end
+
+    local pid = eval('getpid()')
+    local before = monitor_memory_usage(pid)
+    source([[
+      func s:f(...)
+        let x = a:000
+      endfunc
+      for _ in range(10000)
+        call s:f(0)
+      endfor
+    ]])
+    local after = monitor_memory_usage(pid)
+    -- Estimate the limit of max usage as 2x initial usage.
+    check_result({before=before, after=after}, pcall(ok, before.last < after.max))
+    check_result({before=before, after=after}, pcall(ok, before.last * 2 > after.max))
+    -- In this case, garbase collecting is not needed.
+    check_result({before=before, after=after}, pcall(eq, after.last, after.max))
+  end)
+
+  --[[
+  Case: if a local variable captures l: dict, funccall object will not be
+  free until garbage collector runs, but after that memory usage doesn't
+  increase so much even when rerun Xtest.vim since system memory caches.
+  ]]--
+  it('function capture lvars', function()
+    if isasan() then
+      pending('ASAN build is difficult to estimate memory usage')
+    end
+    if iswin() and eval("executable('wmic')")  == 0 then
+      pending('missing "wmic" command')
+    elseif eval("executable('ps')")  == 0 then
+      pending('missing "ps" command')
+    end
+
+    local pid = eval('getpid()')
+    local before = monitor_memory_usage(pid)
+    local fname = source([[
+      if !exists('s:defined_func')
+        func s:f()
+          let x = l:
+        endfunc
+      endif
+      let s:defined_func = 1
+      for _ in range(10000)
+        call s:f()
+      endfor
+    ]])
+    local after = monitor_memory_usage(pid)
+    for _ = 1, 3 do
+      feed_command('so '..fname)
+    end
+    local last = monitor_memory_usage(pid)
+    check_result({before=before, after=after, last=last},
+                 pcall(ok, before.last < last.last))
+    check_result({before=before, after=after, last=last},
+                 pcall(ok, last.last < after.max + (after.last - before.last)))
+  end)
+end)