[erlang-questions] How to view the content of memory using gdb
Monk Boy
boyofmonk@REDACTED
Tue May 21 05:39:36 CEST 2019
Hi all:
My cowboy server occasionally crashe， I suspect that the data of the
query is too large， but I don't know how to view the content of memory
using gdb to find the detail data.
```
sudo gdb /home/q/erlang1705/lib/erlang/erts-6.4/bin/beam.smp core.18269
GNU gdb (GDB) Red Hat Enterprise Linux 7.6.1-80.el7
Copyright (C) 2013 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html
>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law. Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-redhat-linux-gnu".
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>...
Reading symbols from
/home/q/erlang1705/lib/erlang/erts-6.4/bin/beam.smp...done.
[New LWP 18288]
[New LWP 18274]
[New LWP 18276]
[New LWP 18289]
[New LWP 18281]
[New LWP 18273]
[New LWP 18280]
[New LWP 18278]
[New LWP 18277]
[New LWP 18284]
[New LWP 18282]
[New LWP 18275]
[New LWP 18287]
[New LWP 18285]
[New LWP 18291]
[New LWP 18269]
[New LWP 18279]
[New LWP 18286]
[New LWP 18292]
[New LWP 18290]
[New LWP 18271]
[New LWP 18272]
[New LWP 18283]
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib64/libthread_db.so.1".
Core was generated by `/home/q/erlang1705/lib/erlang/erts-6.4/bin/beam.smp
-- -root /home/q/erlang1705'.
Program terminated with signal 6, Aborted.
#0 0x00007fda423b55f7 in raise () from /lib64/libc.so.6
Missing separate debuginfos, use: debuginfo-install
glibc-2.17-106.el7_2.8.x86_64 ncurses-libs-5.9-13.20130511.el7.x86_64
zlib-1.2.7-15.el7.x86_64
(gdb) bt
#0 0x00007fda423b55f7 in raise () from /lib64/libc.so.6
#1 0x00007fda423b6ce8 in abort () from /lib64/libc.so.6
#2 0x000000000045806e in erl_exit_vv (n=1, flush_async=flush_async@REDACTED=0,
fmt=fmt@REDACTED=0x5fbce8 "%s: Cannot %s %lu bytes of memory (of type \"%s\",
thread %d).\n", args1=args1@REDACTED=0x7fda361ba830, args2=args2@REDACTED
=0x7fda361ba848)
at beam/erl_init.c:2123
#3 0x0000000000458308 in erl_exit (n=n@REDACTED=1, fmt=fmt@REDACTED=0x5fbce8
"%s: Cannot %s %lu bytes of memory (of type \"%s\", thread %d).\n") at
beam/erl_init.c:2133
#4 0x000000000043c4c1 in erts_alc_fatal_error (error=error@REDACTED=1,
func=<optimized out>, func@REDACTED=0, n=n@REDACTED=155) at beam/erl_alloc.c:1875
#5 0x000000000043c507 in erts_alloc_n_enomem (n=n@REDACTED=155,
size=size@REDACTED=4723591984) at beam/erl_alloc.c:1900
#6 0x0000000000529023 in erts_alloc (size=4723591984, type=19862) at
beam/erl_alloc.h:228
#7 minor_collection (recl=<synthetic pointer>, nobj=2,
objv=0x7fda415d0380, need=0, p=0x7fda40a46a58) at beam/erl_gc.c:852
#8 erts_garbage_collect (p=p@REDACTED=0x7fda40a46a58, need=need@REDACTED=0,
objv=0x7fda415d0380, nobj=2) at beam/erl_gc.c:450
#9 0x00000000005291d5 in erts_gc_after_bif_call (p=0x7fda40a46a58,
result=0, regs=<optimized out>, arity=<optimized out>) at beam/erl_gc.c:362
#10 0x000000000056e99c in process_main () at beam/beam_emu.c:3578
#11 0x00000000004a734a in sched_thread_func (vesdp=0x7fda398acd40) at
beam/erl_process.c:7695
#12 0x00000000005f6eb5 in thr_wrapper (vtwd=0x7ffcbf9b3b70) at
pthread/ethread.c:106
#13 0x00007fda42951dc5 in start_thread () from /lib64/libpthread.so.0
#14 0x00007fda42476ced in clone () from /lib64/libc.so.6
(gdb) 9
Undefined command: "9". Try "help".
(gdb) f 9
#9 0x00000000005291d5 in erts_gc_after_bif_call (p=0x7fda40a46a58,
result=0, regs=<optimized out>, arity=<optimized out>) at beam/erl_gc.c:362
362 cost = erts_garbage_collect(p, 0, regs, p->arity);
(gdb) source /home/q/lffan.liu/download/otp_src_17.5/erts/etc/unix/
etp-commands.in
%---------------------------------------------------------------------------
% Use etp-help for a command overview and general help.
%
% To use the Erlang support module, the environment variable ROOTDIR
% must be set to the toplevel installation directory of Erlang/OTP,
% so the etp-commands file becomes:
% $ROOTDIR/erts/etc/unix/etp-commands
% Also, erl and erlc must be in the path.
%---------------------------------------------------------------------------
etp-set-max-depth 20
etp-set-max-string-length 100
--------------- System Information ---------------
OTP release: 17
ERTS version: 6.4
Compile date: Thu Apr 11 12:23:01 2019
Arch: x86_64-unknown-linux-gnu
Endianness: Little
Word size: 64-bit
Halfword: no
HiPE support: yes
SMP support: yes
Thread support: yes
Kernel poll: Supported but not used
Debug compiled: no
Lock checking: no
Lock counting: no
Node name: 'ejb_http_server@REDACTED'
Number of schedulers: 8
Number of async-threads: 10
--------------------------------------------------
(gdb) etp-stackdump p
% Stackdump (21): #Cp<lists:reverse/1+0x120>.
#Cp<rfc4627:encode/1+0x48>.
#Cp<http_utils:gen_result/4+0x130>.
#Cp<http_get_history:post_echo/3+0x770>.
#Cp<http_get_history:do_handle/2+0x1c8>.
{http_req,#Port<0.101737>,ranch_tcp,keepalive,<0.15468.5>,#SubBinary<0x4,0,0xde010000:0x13fffcd2>,'HTTP/1.1',{{10,88,193,24},13758},#SubBinary<0xf,0,0x10000:0x13fffd2a>,undefined,80,#SubBinary<0x13,0,0xde000000:0x13fffd5a>,undefined,#SubBinary<0x48,0,0xde010000:0x13fffd8a>,undefined,[],[{#SubBinary<0x4,0,0xde010000:0x13fffffa>,#SubBinary<0xf,0,0x10000:0x1400002a>},{0.000000,#HeapBinary<0x2,0xffff3839>},{#SubBinary<0xf,0,0xd5010000:0x1400026a>,#SubBinary<0xd,0,0x10000:0x1400029a>},{#SubBinary<0xf,0,0xde010000:0x14000382>,#SubBinary<0xa,0,0x10000:0x140003b2>},{#SubBinary<0xa,0,0x10000:0x140004c2>,#SubBinary<0xb,0,0x10000:0x140004f2>},{#SubBinary<0xc,0,0x10000:0x14000612>,#SubBinary<0x21,0,0x10000:0x14000642>},{#SubBinary<0x6,0,0xde010000:0x14000792>,#SubBinary<0x18,0,0x10000:0x140007c2>},{#SubBinary<0x9,0,0xde010000:0x14000912>,#SubBinary<0xe,0,0xde010000:0x14000942>},{#SubBinary<0xd,0,0xde010000:0x14000a72>,#SubBinary<0x5,0,0x10000:0x14000aa2>},{#SubBinary<0xf,0,0xde010000:0x14000bba>,#SubBinary<0xe,0,0x10000:0x14000bea>}],[{0.000000,98},{0.000000,undefined},{0.000000,98}],undefined,[],...}.
#Cp<cowboy_handler:handler_handle/4+0xb8>.
[].
undefined.
[].
#Cp<cowboy_protocol:execute/4+0xb0>.
[].
[].
undefined.
http_get_history.
{state,[{handler,http_get_history},{handler_opts,[]},{listener,http},{dispatch,[{'_',[],[{[#RefcBinary<0x8,0x13fffcd0,0x311dfa20,0x311dfa38,0>],[],http_getusers,[]},{[#RefcBinary<0x7,0x140006f8,0x311c3288,0x311c32a0,0>],[],http_getdeps,[]},{[#RefcBinary<0xb,0x14000878,0x311e9fc0,0x311e9fd8,0>],[],http_getmsgs,[]},{[#RefcBinary<0xd,0x140009d8,0x311c2d10,0x311c2d28,0>],[],http_getonlineuser,[]},{[#RefcBinary<0xe,0x14000b20,0x311c2d50,0x311c2d68,0>],[],http_getonlineuser2,[]},{[#RefcBinary<0xe,0x14000c18,0x311e9e40,0x311e9e58,0>],[],http_get_adjacentmsg,...},{[...],[],...},{[...],...},{...},...]}]},{max_connections,infinity}],false,0,5000,infinity,undefined,false}.
{http_req,#Port<0.101737>,ranch_tcp,keepalive,<0.15468.5>,#SubBinary<0x4,0,0xde010000:0x13fffcd2>,'HTTP/1.1',{{10,88,193,24},13758},#SubBinary<0xf,0,0x10000:0x13fffd2a>,undefined,80,#SubBinary<0x13,0,0xde000000:0x13fffd5a>,undefined,#SubBinary<0x48,0,0xde010000:0x13fffd8a>,undefined,[],[{#SubBinary<0x4,0,0xde010000:0x13fffffa>,#SubBinary<0xf,0,0x10000:0x1400002a>},{#SubBinary<0xe,0,0xde010000:0x140001ba>,#SubBinary<0x2,0,0xde010000:0x140001ea>},{#SubBinary<0xf,0,0xd5010000:0x1400026a>,#SubBinary<0xd,0,0x10000:0x1400029a>},{#SubBinary<0xf,0,0xde010000:0x14000382>,#SubBinary<0xa,0,0x10000:0x140003b2>},{#SubBinary<0xa,0,0x10000:0x140004c2>,#SubBinary<0xb,0,0x10000:0x140004f2>},{#SubBinary<0xc,0,0x10000:0x14000612>,#SubBinary<0x21,0,0x10000:0x14000642>},{#SubBinary<0x6,0,0xde010000:0x14000792>,#SubBinary<0x18,0,0x10000:0x140007c2>},{#SubBinary<0x9,0,0xde010000:0x14000912>,#SubBinary<0xe,0,0xde010000:0x14000942>},{#SubBinary<0xd,0,0xde010000:0x14000a72>,#SubBinary<0x5,0,0x10000:0x14000aa2>},{#SubBinary<0xf,0,0xde010000:0x14000bba>,#SubBinary<0xe,0,0x10000:0x14000bea>}],[{0.000000,98},{0.000000,[Cannot
access memory at address 0x18
(gdb) etp-process
etp-process-info etp-process-memory-info etp-processes
etp-processes-memory
(gdb) etp-process-info p
Pid: <0.15468.5>
State: garbage-collecting | running | active | prq-prio-normal |
usr-prio-normal | act-prio-normal
Current function: lists:reverse/2
CP: #Cp<lists:reverse/1+0x120>
I: #Cp<0x3ff50a70>
Heap size: 492040832
Mbuf size: 160000
Msgq len: 0 (inner=0, outer=0)
Parent: <0.600.0>
Pointer: (Process *) 0x7fda40a46a58
```
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