./samples/sample-bt-leaks.sxx 报错

[金海浪]

你好，春哥！

我在尝试抓取内存泄露火焰图时，出出现以下错误：

root@debianvm:/home/jinhailang/stapxx# ./samples/sample-bt-leaks.sxx -x 30408 -v --arg time=5 > a.bt

Pass 1: parsed user script and 466 library scripts using 114076virt/46948res/6380shr/40724data kb, in 0usr/190sys/193real ms.

semantic error: while resolving probe point: identifier 'process' at <input>:17:7

        source: probe process("/usr/local/openresty/lualib/cjson.so").function("malloc").return,

                      ^

semantic error: no match (similar functions: die, _fini, _init, json_decode, json_encode)

semantic error: while resolving probe point: identifier 'process' at :18:7

        source:       process("/usr/local/openresty/lualib/cjson.so").function("calloc").return,

                      ^

semantic error: no match (similar functions: die, _fini, _init, json_decode, json_encode)

semantic error: while resolving probe point: identifier 'process' at :19:7

        source:       process("/usr/local/openresty/lualib/cjson.so").function("realloc").return

                      ^

semantic error: no match (similar functions: die, _fini, _init, decode_hex4, json_encode)

semantic error: while resolving probe point: identifier 'process' at :74:7

        source: probe process("/usr/local/openresty/lualib/cjson.so").function("free")

                      ^

semantic error: no match (similar functions: die, _fini, strbuf_free, _init, strbuf_new)

Pass 2: analyzed script: 2 probes, 186 functions, 3 embeds, 5 globals using 115792virt/49980res/7728shr/42440data kb, in 0usr/50sys/59real ms.

Pass 2: analysis failed.  [man error::pass2]

Tip: /usr/share/doc/systemtap/README.Debian should help you get started.

我找到类似的问题回复：https://groups.google.com/forum/#!msg/openresty/pVfoi5iV-2U/0DiD0GaQMfAJ

但是，我的 stapxx 是直接 git clone 下来的，是最新版的。

然后，我展开了脚本，看不太明白：

root@debianvm:/home/jinhailang/stapxx# ./samples/sample-bt-leaks.sxx -x 30408 -v --arg time=5  --dump-src

#!/usr/bin/env stap

# Copyright (C) Yichun Zhang (agentzh)

global ptr2bt

global ptr2size

global bt_stats

global quit

global free_misses

probe begin

{

    warn(sprintf("Start tracing %d (/usr/local/openresty/nginx/sbin/nginx)...", target()))

    warn("Wait for 5 sec to complete.\n")

}

probe process("/usr/local/openresty/lualib/cjson.so").function("malloc").return,

      process("/usr/local/openresty/lualib/cjson.so").function("calloc").return,

      process("/usr/local/openresty/lualib/cjson.so").function("realloc").return

{

    if (pid() == target()) {

        //printf("Hit %s\n", probefunc())

        if (quit) {

            if (free_misses) {

                warn(sprintf("free misses: %d", free_misses))

            }

            foreach (bt in bt_stats) {

                print_ustack(bt)

                printf("\t%d\n", @sum(bt_stats[bt]))

            }

            exit()

        } else {

            if (@defined($oldmem)) {

                //printf("free %p in realloc\n", $oldmem)

                ptr = $oldmem

                bt = ptr2bt[ptr]

                delete ptr2bt[ptr]

                bytes = ptr2size[ptr]

                delete ptr2size[ptr]

                bt_stats[bt] <<< -bytes

                if (@sum(bt_stats[bt]) == 0) {

                    delete bt_stats[bt]

                }

            }

            ptr = returnval()

            if (ptr) {

                // here we use a hack specific to glibc's implementation

                // to get the size of the memory block because we

                // may not get the value of the $bytes parameter reliably.

                p = ptr - &@cast(0, "size_t")[1]

                size = @cast(p, "size_t")[0] & ~(&@cast(0, "size_t")[1] - 1)

                //printf("alloc: %p (bytes %d)\n", ptr, size)

                bt = ubacktrace()

                ptr2bt[ptr] = bt

                ptr2size[ptr] = size

                bt_stats[bt] <<< size

            } else {

                warn("NULL returned")

            }

        }

    }

}

使用 /samples/lj-lua-bt.sxx --skip-badvars -x 30408 > tmp.bt 抓取 CPU 火焰图都是正常的，这个问题挺困扰我的，麻烦有空指点一下吧，感谢！

[tokers]

Hello!

从上面你贴出来的报错信息来看，应该是你的 cjson.so 编译的时候没有带上调试参数，可以尝试重新编译下 cjson.so。

[金海浪]

带上调试参数，重新编译后，问题解决。

Makefile 已经提供了调试选项，去掉注释就行：

```

 CFLAGS =            -g -Wall -pedantic -fno-inline

 #CFLAGS =            -O3 -Wall -pedantic -DNDEBUG

```

多谢 @tokers

在 2018年7月5日星期四 UTC+8下午3:23:06，tokers写道：