[axel-devel] [axel-Bugs][313564] An order violation which may cause a dead loop(sometimes crash)
Zhai Xiang
xiangzhai83 at gmail.com
Fri Mar 9 14:07:24 UTC 2012
Hi Zhang,
Thanks for your setup_thread callback DEBUG :)
I chose WSAEventSelect Asynchronous I/O instead of select(), and
porting to NATIVE WIN32 without Cygwin, it only paused when read/recv
by CreateThread from HTTP request socket BUT NO CRASH.
And original Axel allocated buffer for read/write without memset() in
each thread.
My Axel-WIN32 SVN address goes here
http://xsandbox.googlecode.com/svn/trunk/axel-win32
2012/3/9 <axel-bugs at alioth.debian.org>:
> Bugs item #313564, was opened at 2012-03-09 18:23 by Mingxing Zhang
> You can respond by visiting:
> https://alioth.debian.org/tracker/?func=detail&atid=413085&aid=313564&group_id=100070
>
> Status: Open
> Priority: 3
> Submitted By: Mingxing Zhang (zhangmx-guest)
> Assigned to: Nobody (None)
> Summary: An order violation which may cause a dead loop(sometimes crash)
>
>
> Initial Comment:
> Hi, axel developers:
> This bug is trigger by a pintool tailored for detecting concurrency bug, so it may hardly to be exposed in realworld. (fotunatly it's easy to reproduce).
> The main cause of this bug is that the function axel.c:setup_thread is excuted in a new thread created by axel.c:axel_start. Although it's rarely happended, if this thread excute untolerately slow /*excute line 538 conn->last_transfer = gettime(); and line 539 conn->state = 0; later than line 389 if( !axel->conn[i].enabled &&...) and line 417 if( gettime() > axel->conn[i].last_transfer + axel->conf->reconnect_delay )*/, it will be restarted by axel.c:axel_do(line 419). So if setup_thread always excute slowly there will be a dead loop.(sometimes there will be a crash)
>
> How to reproduce:
> add sleep(50); before axel.c:538 conn->last_transfer = gettime(); (axel-2.4)
>
> But I have no idea about why it may crash, maybe the following error message will help.
> --error message when crash--
> mingxingzhang:bin$./axel -n 4 http://10.0.1.113:8087/mysql.tar.gz
> Initializing download: http://10.0.1.113:8087/mysql.tar.gz
> tcp_connect( 10.0.1.113, 8087 ) = 33793
> --- Sending request ---
> GET /mysql.tar.gz HTTP/1.0
> Host: 10.0.1.113
> Range: bytes=1-
> User-Agent: Axel 2.4 (Linux)
> --- End of request ---
> --- Reply headers ---
> HTTP/1.1 206 Partial Content
> Date: Fri, 09 Mar 2012 08:19:54 GMT
> Server: Apache/2.4.1 (Unix) PHP/5.4.0
> Last-Modified: Thu, 08 Mar 2012 03:04:18 GMT
> ETag: "67d51-4bab288265080"
> Accept-Ranges: bytes
> Content-Length: 425296
> Content-Range: bytes 1-425296/425297
> Connection: close
> Content-Type: application/x-gzip
> --- End of headers ---
> File size: 425297 bytes
> Downloading 0-106323 using conn. 0
> Downloading 106324-212648 using conn. 1
> Downloading 212649-318973 using conn. 2
> Downloading 318974-425296 using conn. 3
> Opening output file mysql.tar.gz.1
> State file found: 0 bytes downloaded, 425297 to go.
> Starting download
> tcp_connect( 10.0.1.113, 8087 ) = tcp_connect( 10.0.1.113, 8087 ) = tcp_connect( 10.0.1.113, 8087 ) = tcp_connect( 10.0.1.113, 8087 ) = 33794
> --- Sending request ---
> GET /mysql.tar.gz HTTP/1.0
> Host: 10.0.1.113
> Range: bytes=318974-425296
> User-Agent: Axel 2.4 (Linux)
> --- End of request ---
> 33795
> --- Sending request ---
> GET /mysql.tar.gz HTTP/1.0
> Host: 10.0.1.113
> Range: bytes=212649-318973
> User-Agent: Axel 2.4 (Linux)
> --- End of request ---
> 33796
> --- Sending request ---
> GET /mysql.tar.gz HTTP/1.0
> Host: 10.0.1.113
> Range: bytes=106324-212648
> User-Agent: Axel 2.4 (Linux)
> --- End of request ---
> 33797
> --- Sending request ---
> GET /mysql.tar.gz HTTP/1.0
> Host: 10.0.1.113
> User-Agent: Axel 2.4 (Linux)
> --- End of request ---
> --- Reply headers ---
> HTTP/1.1 206 Partial Content
> Date: Fri, 09 Mar 2012 08:19:54 GMT
> Server: Apache/2.4.1 (Unix) PHP/5.4.0
> Last-Modified: Thu, 08 Mar 2012 03:04:18 GMT
> ETag: "67d51-4bab288265080"
> Accept-Ranges: bytes
> Content-Length: 106323
> Content-Range: bytes 318974-425296/425297
> Connection: close
> Content-Type: application/x-gzip
> --- End of headers ---
> --- Reply headers ---
> HTTP/1.1 206 Partial Content
> Date: Fri, 09 Mar 2012 08:19:54 GMT
> Server: Apache/2.4.1 (Unix) PHP/5.4.0
> Last-Modified: Thu, 08 Mar 2012 03:04:18 GMT
> ETag: "67d51-4bab288265080"
> Accept-Ranges: bytes
> Content-Length: 106325
> Content-Range: bytes 212649-318973/425297
> Connection: close
> Content-Type: application/x-gzip
> --- End of headers ---
> --- Reply headers ---
> HTTP/1.1 206 Partial Content
> Date: Fri, 09 Mar 2012 08:19:54 GMT
> Server: Apache/2.4.1 (Unix) PHP/5.4.0
> Last-Modified: Thu, 08 Mar 2012 03:04:18 GMT
> ETag: "67d51-4bab288265080"
> Accept-Ranges: bytes
> Content-Length: 106325
> Content-Range: bytes 106324-212648/425297
> Connection: close
> Content-Type: application/x-gzip
> --- End of headers ---
> --- Reply headers ---
> HTTP/1.1 200 OK
> Date: Fri, 09 Mar 2012 08:19:54 GMT
> Server: Apache/2.4.1 (Unix) PHP/5.4.0
> Last-Modified: Thu, 08 Mar 2012 03:04:18 GMT
> ETag: "67d51-4bab288265080"
> Accept-Ranges: bytes
> Content-Length: 425297
> Connection: close
> Content-Type: application/x-gzip
> --- End of headers ---
> --- Sending request ---
> GET /mysql.tar.gz HTTP/1.0
> Host: 10.0.1.113
> Range: bytes=318974-425296
> User-Agent: Axel 2.4 (Linux)
> --- End of request ---
> *** buffer overflow detected ***: ./axel terminated
> ======= Backtrace: =========
> /lib/i386-linux-gnu/libc.so.6(__fortify_fail+0x45)[0x34d8d5]
> --- Sending request ---
> GET /mysql.tar.gz HTTP/1.0
> Host: 10.0.1.113
> Range: bytes=212649-318973
> User-Agent: Axel 2.4 (Linux)
> --- End of request ---
> --- Sending request ---
> GET /mysql.tar.gz HTTP/1.0
> Host: 10.0.1.113
> Range: bytes=106324-212648
> User-Agent: Axel 2.4 (Linux)
> --- End of request ---
> --- Sending request ---
> GET /mysql.tar.gz HTTP/1.0
> Host: 10.0.1.113
> User-Agent: Axel 2.4 (Linux)
> --- End of request ---
> /lib/i386-linux-gnu/libc.so.6(+0xe66d7)[0x34c6d7]
> /lib/i386-linux-gnu/libc.so.6(+0xe5b3f)[0x34bb3f]
> ./axel[0x804da8e]
> ./axel[0x804c6d4]
> ./axel[0x804b497]
> /lib/i386-linux-gnu/libpthread.so.0(+0x6d31)[0xd61d31]
> /lib/i386-linux-gnu/libc.so.6(clone+0x5e)[0x3380ce]
> ======= Memory map: ========
> 00265000-00266000 r-xp 00000000 00:00 0 [vdso]
> 00266000-003dc000 r-xp 00000000 08:01 5243813 /lib/i386-linux-gnu/libc-2.13.so
> 003dc000-003de000 r--p 00176000 08:01 5243813 /lib/i386-linux-gnu/libc-2.13.so
> 003de000-003df000 rw-p 00178000 08:01 5243813 /lib/i386-linux-gnu/libc-2.13.so
> 003df000-003e2000 rw-p 00000000 00:00 0
> 004bc000-004da000 r-xp 00000000 08:01 5243800 /lib/i386-linux-gnu/ld-2.13.so
> 004da000-004db000 r--p 0001d000 08:01 5243800 /lib/i386-linux-gnu/ld-2.13.so
> 004db000-004dc000 rw-p 0001e000 08:01 5243800 /lib/i386-linux-gnu/ld-2.13.so
> 00549000-00565000 r-xp 00000000 08:01 5243834 /lib/i386-linux-gnu/libgcc_s.so.1
> 00565000-00566000 r--p 0001b000 08:01 5243834 /lib/i386-linux-gnu/libgcc_s.so.1
> 00566000-00567000 rw-p 0001c000 08:01 5243834 /lib/i386-linux-gnu/libgcc_s.so.1
> 00d5b000-00d72000 r-xp 00000000 08:01 5243873 /lib/i386-linux-gnu/libpthread-2.13.so
> 00d72000-00d73000 r--p 00016000 08:01 5243873 /lib/i386-linux-gnu/libpthread-2.13.so
> 00d73000-00d74000 rw-p 00017000 08:01 5243873 /lib/i386-linux-gnu/libpthread-2.13.so
> 00d74000-00d76000 rw-p 00000000 00:00 0
> 08048000-08053000 r-xp 00000000 08:01 2105096 /home/mingxingzhang/axel-2.4/bin/bin/axel
> 08053000-08054000 r--p 0000a000 08:01 2105096 /home/mingxingzhang/axel-2.4/bin/bin/axel
> 08054000-08055000 rw-p 0000b000 08:01 2105096 /home/mingxingzhang/axel-2.4/bin/bin/axel
> 090c8000-090e9000 rw-p 00000000 00:00 0 [heap]
> b565d000-b565e000 ---p 00000000 00:00 0
> b565e000-b5e5e000 rw-p 00000000 00:00 0
> b5e5e000-b5e5f000 ---p 00000000 00:00 0
> b5e5f000-b665f000 rw-p 00000000 00:00 0
> b665f000-b6660000 ---p 00000000 00:00 0
> b6660000-b6e60000 rw-p 00000000 00:00 0
> b6e60000-b6e61000 ---p 00000000 00:00 0
> b6e61000-b7662000 rw-p 00000000 00:00 0
> b7662000-b7663000 r--p 0043a000 08:01 7084893 /usr/lib/locale/locale-archive
> b7663000-b76a3000 r--p 002bd000 08:01 7084893 /usr/lib/locale/locale-archive
> b76a3000-b78a3000 r--p 00000000 08:01 7084893 /usr/lib/locale/locale-archive
> b78a3000-b78a5000 rw-p 00000000 00:00 0
> b78b4000-b78b6000 rw-p 00000000 00:00 0
> bf8ce000-bf8ef000 rw-p 00000000 00:00 0 [stack]
> Aborted
>
>
> ----------------------------------------------------------------------
>
> You can respond by visiting:
> https://alioth.debian.org/tracker/?func=detail&atid=413085&aid=313564&group_id=100070
>
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