[Tarantool-patches] [PATCH luajit v2] sysprof: improve parser's memory footprint

Wed May 24 23:36:02 MSK 2023

Hi!
Forgot to include my answers to questions.

> Also, it fixes a bug in the AVL-tree implementation,
> which produced unnecessary inserts of values into nodes.

Q: Should it be any test for this?
Also, may be this should be done in the separate commit (not patch?).

A: It is such a silly bug, that no, I don't believe it's needed. I've literlly
changed the line from `table.insert(node.value, value)` to
`node.value = value`. And we still have tests for the AVL tree itself, so
we know for sure that this change doesn't break anything.

NB: CI is red in LuaJIT repo because this patch requires changes in the
tarantool repo, so please refer to CI runs in PR.

--
Best regards,
Maxim Kokryashkin

>Среда, 24 мая 2023, 23:35 +03:00 от Maxim Kokryashkin <max.kokryashkin at gmail.com>:
> 
>This patch reduces sysprof's parser memory footprint,
>by avoiding reading all callchains before collapsing them.
>Instead of it, parser merges stacks immediately after
>reading them and stores counts in a lua table.
>
>Also, it fixes a bug in the AVL-tree implementation,
>which produced unnecessary inserts of values into nodes.
>---
>
>Changes in v2:
>- Fixed comments as per review by Sergey.
>
>Branch:  https://github.com/tarantool/luajit/tree/fckxorg/gh-8700-sysprof-parser-refactoring
>PR:  https://github.com/tarantool/tarantool/pull/8703
>
> tools/CMakeLists.txt | 2 -
> tools/sysprof.lua | 27 +-------
> tools/sysprof/collapse.lua | 124 ------------------------------------
> tools/sysprof/parse.lua | 127 +++++++++++++++++++++++++++----------
> tools/utils/avl.lua | 2 +-
> tools/utils/symtab.lua | 2 +-
> 6 files changed, 97 insertions(+), 187 deletions(-)
> delete mode 100755 tools/sysprof/collapse.lua
>
>diff --git a/tools/CMakeLists.txt b/tools/CMakeLists.txt
>index dd7ec6bd..3a919433 100644
>--- a/tools/CMakeLists.txt
>+++ b/tools/CMakeLists.txt
>@@ -112,7 +112,6 @@ else()
>   add_custom_target(tools-parse-sysprof EXCLUDE_FROM_ALL DEPENDS
>     luajit-parse-sysprof
>     sysprof/parse.lua
>- sysprof/collapse.lua
>     sysprof.lua
>     utils/bufread.lua
>     utils/symtab.lua
>@@ -121,7 +120,6 @@ else()
> 
>   install(FILES
>       ${CMAKE_CURRENT_SOURCE_DIR}/sysprof/parse.lua
>- ${CMAKE_CURRENT_SOURCE_DIR}/sysprof/collapse.lua
>     DESTINATION ${LUAJIT_DATAROOTDIR}/sysprof
>     PERMISSIONS
>       OWNER_READ OWNER_WRITE
>diff --git a/tools/sysprof.lua b/tools/sysprof.lua
>index 1afab195..be2a0565 100644
>--- a/tools/sysprof.lua
>+++ b/tools/sysprof.lua
>@@ -1,13 +1,10 @@
> local bufread = require "utils.bufread"
> local sysprof = require "sysprof.parse"
> local symtab = require "utils.symtab"
>-local misc = require "sysprof.collapse"
> 
> local stdout, stderr = io.stdout, io.stderr
> local match, gmatch = string.match, string.gmatch
> 
>-local split_by_vmstate = false
>-
> -- Program options.
> local opt_map = {}
> 
>@@ -28,10 +25,6 @@ Supported options are:
>   os.exit(0)
> end
> 
>-function opt_map.split()
>- split_by_vmstate = true
>-end
>-
> -- Print error and exit with error status.
> local function opterror(...)
>   stderr:write("luajit-parse-sysprof.lua: ERROR: ", ...)
>@@ -85,28 +78,14 @@ local function parseargs(args)
>   return args[args.argn]
> end
> 
>-local function traverse_calltree(node, prefix)
>- if node.is_leaf then
>- print(prefix..' '..node.count)
>- end
>-
>- local sep_prefix = #prefix == 0 and prefix or prefix..';'
>-
>- for name,child in pairs(node.children) do
>- traverse_calltree(child, sep_prefix..name)
>- end
>-end
>-
> local function dump(inputfile)
>   local reader = bufread.new(inputfile)
>-
>   local symbols = symtab.parse(reader)
>-
>   local events = sysprof.parse(reader, symbols)
>- local calltree = misc.collapse(events, symbols, split_by_vmstate)
>-
>- traverse_calltree(calltree, '')
> 
>+ for stack, count in pairs(events) do
>+ print(stack, count)
>+ end
>   os.exit(0)
> end
> 
>diff --git a/tools/sysprof/collapse.lua b/tools/sysprof/collapse.lua
>deleted file mode 100755
>index 3d83d5ea..00000000
>--- a/tools/sysprof/collapse.lua
>+++ /dev/null
>@@ -1,124 +0,0 @@
>-local parse = require "sysprof.parse"
>-local vmdef = require "jit.vmdef"
>-local symtab = require "utils.symtab"
>-
>-local VMST_NAMES = {
>- [parse.VMST.INTERP] = "VMST_INTERP",
>- [parse.VMST.LFUNC] = "VMST_LFUNC",
>- [parse.VMST.FFUNC] = "VMST_FFUNC",
>- [parse.VMST.CFUNC] = "VMST_CFUNC",
>- [parse.VMST.GC] = "VMST_GC",
>- [parse.VMST.EXIT] = "VMST_EXIT",
>- [parse.VMST.RECORD] = "VMST_RECORD",
>- [parse.VMST.OPT] = "VMST_OPT",
>- [parse.VMST.ASM] = "VMST_ASM",
>- [parse.VMST.TRACE] = "VMST_TRACE",
>-}
>-
>-local M = {}
>-
>-local function new_node(name, is_leaf)
>- return {
>- name = name,
>- count = 0,
>- is_leaf = is_leaf,
>- children = {}
>- }
>-end
>-
>--- insert new child into a node (or increase counter in existing one)
>-local function insert(name, node, is_leaf)
>- if node.children[name] == nil then
>- node.children[name] = new_node(name, is_leaf)
>- end
>-
>- local child = node.children[name]
>- child.count = child.count + 1
>-
>- return child
>-end
>-
>-local function insert_lua_callchain(chain, lua, symbols)
>- local ins_cnt = 0
>- for _,fr in pairs(lua.callchain) do
>- local name_lua
>-
>- ins_cnt = ins_cnt + 1
>- if fr.type == parse.FRAME.FFUNC then
>- name_lua = vmdef.ffnames[fr.ffid]
>- else
>- name_lua = symtab.demangle(symbols, {
>- addr = fr.addr,
>- line = fr.line,
>- gen = fr.gen
>- })
>- if lua.trace.traceno ~= nil and lua.trace.addr == fr.addr and
>- lua.trace.line == fr.line then
>- name_lua = symtab.demangle(symbols, {
>- addr = fr.addr,
>- traceno = lua.trace.traceno,
>- gen = fr.gen
>- })
>- end
>-
>- if fr.type == parse.FRAME.CFUNC then
>- -- C function encountered, the next chunk
>- -- of frames is located on the C stack.
>- break
>- end
>- end
>-
>- table.insert(chain, 1, { name = name_lua })
>- end
>- table.remove(lua.callchain, ins_cnt)
>-end
>-
>--- merge lua and host callchains into one callchain representing
>--- transfer of control
>-local function merge(event, symbols, sep_vmst)
>- local cc = {}
>-
>- for _,h_fr in pairs(event.host.callchain) do
>- local name_host = symtab.demangle(symbols, {
>- addr = h_fr.addr,
>- gen = h_fr.gen
>- })
>- table.insert(cc, 1, { name = name_host })
>-
>- if string.match(name_host, '^lua_cpcall') ~= nil then
>- -- Any C function is present on both the C and the Lua
>- -- stacks. It is more convenient to get its info from the
>- -- host stack, since it has information about child frames.
>- table.remove(event.lua.callchain, 1)
>- end
>-
>- if string.match(name_host, '^lua_p?call') ~= nil then
>- insert_lua_callchain(cc, event.lua, symbols)
>- end
>-
>- end
>-
>- if sep_vmst == true then
>- table.insert(cc, { name = VMST_NAMES[event.lua.vmstate] })
>- end
>-
>- return cc
>-end
>-
>--- Collapse all the events into call tree
>-function M.collapse(events, symbols, sep_vmst)
>- local root = new_node('root', false)
>-
>- for _,ev in pairs(events) do
>- local callchain = merge(ev, symbols, sep_vmst)
>- local curr_node = root
>- for i=#callchain,1,-1 do
>- curr_node = insert(callchain[i].name, curr_node, false)
>- end
>- insert('', curr_node, true)
>- end
>-
>- return root
>-end
>-
>-return M
>diff --git a/tools/sysprof/parse.lua b/tools/sysprof/parse.lua
>index 5b52f104..806297eb 100755
>--- a/tools/sysprof/parse.lua
>+++ b/tools/sysprof/parse.lua
>@@ -2,6 +2,7 @@
> -- The format spec can be found in <src/lj_sysprof.h>.
> 
> local symtab = require "utils.symtab"
>+local vmdef = require "jit.vmdef"
> 
> local string_format = string.format
> 
>@@ -10,7 +11,7 @@ local LJP_CURRENT_VERSION = 2
> 
> local M = {}
> 
>-M.VMST = {
>+local VMST = {
>   INTERP = 0,
>   LFUNC = 1,
>   FFUNC = 2,
>@@ -25,13 +26,14 @@ M.VMST = {
> }
> 
> 
>-M.FRAME = {
>+local FRAME = {
>   LFUNC = 1,
>   CFUNC = 2,
>   FFUNC = 3,
>   BOTTOM = 0x80
> }
> 
>+
> local STREAM_END = 0x80
> local SYMTAB_LFUNC_EVENT = 10
> local SYMTAB_CFUNC_EVENT = 11
>@@ -54,42 +56,40 @@ local function new_event()
>   }
> end
> 
>-local function parse_lfunc(reader, event, symbols)
>+local function parse_lfunc(reader, symbols)
>   local addr = reader:read_uleb128()
>   local line = reader:read_uleb128()
>   local loc = symtab.loc(symbols, { addr = addr, line = line })
>- loc.type = M.FRAME.LFUNC
>- table.insert(event.lua.callchain, 1, loc)
>+ loc.type = FRAME.LFUNC
>+ return symtab.demangle(symbols, loc)
> end
> 
>-local function parse_ffunc(reader, event, _)
>+local function parse_ffunc(reader, _)
>   local ffid = reader:read_uleb128()
>- table.insert(event.lua.callchain, 1, {
>- type = M.FRAME.FFUNC,
>- ffid = ffid,
>- })
>+ return vmdef.ffnames[ffid]
> end
> 
>-local function parse_cfunc(reader, event, symbols)
>+local function parse_cfunc(reader, symbols)
>   local addr = reader:read_uleb128()
>   local loc = symtab.loc(symbols, { addr = addr })
>- loc.type = M.FRAME.CFUNC
>- table.insert(event.lua.callchain, 1, loc)
>+ loc.type = FRAME.CFUNC
>+ return symtab.demangle(symbols, loc)
> end
> 
> local frame_parsers = {
>- [M.FRAME.LFUNC] = parse_lfunc,
>- [M.FRAME.FFUNC] = parse_ffunc,
>- [M.FRAME.CFUNC] = parse_cfunc
>+ [FRAME.LFUNC] = parse_lfunc,
>+ [FRAME.FFUNC] = parse_ffunc,
>+ [FRAME.CFUNC] = parse_cfunc
> }
> 
> local function parse_lua_callchain(reader, event, symbols)
>   while true do
>     local frame_header = reader:read_octet()
>- if frame_header == M.FRAME.BOTTOM then
>+ if frame_header == FRAME.BOTTOM then
>       break
>     end
>- frame_parsers[frame_header](reader, event, symbols)
>+ local name = frame_parsers[frame_header](reader, symbols)
>+ table.insert(event.lua.callchain, 1, {name = name, type = frame_header})
>   end
> end
> 
>@@ -100,7 +100,7 @@ local function parse_host_callchain(reader, event, symbols)
> 
>   while addr ~= 0 do
>     local loc = symtab.loc(symbols, { addr = addr })
>- table.insert(event.host.callchain, 1, loc)
>+ table.insert(event.host.callchain, 1, symtab.demangle(symbols, loc))
>     addr = reader:read_uleb128()
>   end
> end
>@@ -108,10 +108,20 @@ end
> --~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~--
> 
> local function parse_trace_callchain(reader, event, symbols)
>- event.lua.trace.traceno = reader:read_uleb128()
>- event.lua.trace.addr = reader:read_uleb128()
>- event.lua.trace.line = reader:read_uleb128()
>- event.lua.trace.gen = symtab.loc(symbols, event.lua.trace).gen
>+ local loc = {}
>+ loc.traceno = reader:read_uleb128()
>+ loc.addr = reader:read_uleb128()
>+ loc.line = reader:read_uleb128()
>+
>+ local gen = symtab.loc(symbols, loc).gen
>+ local name_lua = symtab.demangle(symbols, {
>+ addr = loc.addr,
>+ traceno = loc.traceno,
>+ gen = gen
>+ })
>+ event.lua.trace = loc
>+ event.lua.trace.gen = gen
>+ event.lua.trace.name = name_lua
> end
> 
> --~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~--
>@@ -143,18 +153,63 @@ local function parse_symtab(reader, symbols, vmstate)
> end
> 
> local event_parsers = {
>- [M.VMST.INTERP] = parse_host_only,
>- [M.VMST.LFUNC] = parse_lua_host,
>- [M.VMST.FFUNC] = parse_lua_host,
>- [M.VMST.CFUNC] = parse_lua_host,
>- [M.VMST.GC] = parse_host_only,
>- [M.VMST.EXIT] = parse_host_only,
>- [M.VMST.RECORD] = parse_host_only,
>- [M.VMST.OPT] = parse_host_only,
>- [M.VMST.ASM] = parse_host_only,
>- [M.VMST.TRACE] = parse_trace,
>+ [VMST.INTERP] = parse_host_only,
>+ [VMST.LFUNC] = parse_lua_host,
>+ [VMST.FFUNC] = parse_lua_host,
>+ [VMST.CFUNC] = parse_lua_host,
>+ [VMST.GC] = parse_host_only,
>+ [VMST.EXIT] = parse_host_only,
>+ [VMST.RECORD] = parse_host_only,
>+ [VMST.OPT] = parse_host_only,
>+ [VMST.ASM] = parse_host_only,
>+ [VMST.TRACE] = parse_trace,
> }
> 
>+local function insert_lua_callchain(chain, lua)
>+ local ins_cnt = 0
>+ local name_lua
>+ for _, fr in ipairs(lua.callchain) do
>+ ins_cnt = ins_cnt + 1
>+ if fr.type == FRAME.CFUNC then
>+ -- C function encountered, the next chunk
>+ -- of frames is located on the C stack.
>+ break
>+ end
>+ name_lua = fr.name
>+
>+ if fr.type == FRAME.LFUNC
>+ and lua.trace.traceno ~= nil
>+ and lua.trace.addr == fr.addr
>+ and lua.trace.line == fr.line
>+ then
>+ name_lua = lua.trace.name
>+ end
>+
>+ table.insert(chain, name_lua)
>+ end
>+ table.remove(lua.callchain, ins_cnt)
>+end
>+
>+local function merge(event)
>+ local callchain = {}
>+
>+ for _, name_host in ipairs(event.host.callchain) do
>+ table.insert(callchain, name_host)
>+ if string.match(name_host, '^lua_cpcall') ~= nil then
>+ -- Any C function is present on both the C and the Lua
>+ -- stacks. It is more convenient to get its info from the
>+ -- host stack, since it has information about child frames.
>+ table.remove(event.lua.callchain)
>+ end
>+
>+ if string.match(name_host, '^lua_p?call') ~= nil then
>+ insert_lua_callchain(callchain, event.lua)
>+ end
>+
>+ end
>+ return table.concat(callchain, ';') .. ';'
>+end
>+
> local function parse_event(reader, events, symbols)
>   local event = new_event()
> 
>@@ -171,8 +226,9 @@ local function parse_event(reader, events, symbols)
>   event.lua.vmstate = vmstate
> 
>   event_parsers[vmstate](reader, event, symbols)
>-
>- table.insert(events, event)
>+ local callchain = merge(event)
>+ local cur_cnt = events[callchain]
>+ events[callchain] = (cur_cnt or 0) + 1
>   return true
> end
> 
>@@ -203,4 +259,5 @@ function M.parse(reader, symbols)
>   return events
> end
> 
>+
> return M
>diff --git a/tools/utils/avl.lua b/tools/utils/avl.lua
>index d5baa534..098f58ec 100644
>--- a/tools/utils/avl.lua
>+++ b/tools/utils/avl.lua
>@@ -86,7 +86,7 @@ function M.insert(node, key, value)
>   elseif key > node.key then
>     node.right = M.insert(node.right, key, value)
>   else
>- table.insert(node.value, value)
>+ node.value = value
>   end
> 
>   update_height(node)
>diff --git a/tools/utils/symtab.lua b/tools/utils/symtab.lua
>index c26a9e8c..7f6c78f0 100644
>--- a/tools/utils/symtab.lua
>+++ b/tools/utils/symtab.lua
>@@ -176,7 +176,7 @@ function M.demangle(symtab, loc)
>   local key, value = avl.floor(symtab.cfunc, addr)
> 
>   if key then
>- return string_format("%s:%#x", value[gen].name, key)
>+ return string_format("%s:%#x", value.name, key)
>   end
> 
>   return string_format("CFUNC %#x", addr)
>--
>2.40.1

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