I'm testing this linked-in driver (JSON parser/encoder) <br><br> <a href="http://github.com/davisp/eep0018/tree/master">http://github.com/davisp/eep0018/tree/master</a><br><br>The problem occurs with the 64-bit SMP emulator. I'm building and running on Red Hat Enterprise Linux 5 (gcc version 4.1.2 20070626 (Red Hat 4.1.2-14)) -- see full details at end of email.<br>
<br>If I use the linked-in driver from more than one process at a time, it frequently causes beam to segv with:<br>
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<p class="MsoNormal">> 0 erts_ddll_proc_dead PC=0x0044eff3,
FP=0x41f5a0e0
[/rhel5pdi/cnewcom/Erlang/erlang/erts-5.6.5/bin/beam.smp]</p>
<p class="MsoNormal"> 1 continue_exit_process PC=0x004a92d4,
FP=0x41f5a190 [/rhel5pdi/cnewcom/Erlang/erlang/erts-5.6.5/bin/beam.smp]</p>
<p class="MsoNormal"> 2 erts_do_exit_process PC=0x004a9137,
FP=0x41f5a1c0
[/rhel5pdi/cnewcom/Erlang/erlang/erts-5.6.5/bin/beam.smp]</p>
<p class="MsoNormal"> 3 process_main
PC=0x00538b40, FP=0x41f5c0d0
[/rhel5pdi/cnewcom/Erlang/erlang/erts-5.6.5/bin/beam.smp]</p>
<p class="MsoNormal"> 4 exit_sched_thr PC=0x004a3082,
FP=0x41f5c0f0
[/rhel5pdi/cnewcom/Erlang/erlang/erts-5.6.5/bin/beam.smp]</p>
<p class="MsoNormal"> 5 reinit_mutexes PC=0x005cafe9,
FP=0x41f5c120
[/rhel5pdi/cnewcom/Erlang/erlang/erts-5.6.5/bin/beam.smp]</p>
<br>
(I haven't yet built the emulator with -g, so I don't have any more information than that, sorry)<br>
<br>I suspect the problem occurs because my test code was calling
erl_ddll:load_driver() from every process that ever needs to use the
driver. (I know that's not optimum; this was only a test hack, not production code.)<br>
<br>
The problem seems to disappear if I switch to the non-SMP emulator (I can't rule it out, but it hasn't occured in a long test-run).<br>
<br>
The problem also seems to disappear if I use the 32-bit SMP emulator
(however, in that case I'm running on a different OS and compiler (gcc version 3.2.3 20030502 (Red Hat Linux 3.2.3-47)<br>
<br>My code looked like:<br><br> 112 safe_json_to_term(JsonTextBin) -><br> 113<br> 114 %% As ErlangFastJSON currently returns an untagged message and<br> 115 %% does a non-selective receive, it can return entirely the wrong<br>
116 %% response. So we need to use a temporary process for now.<br> 117<br> 118 CallerPid = self(),<br> 119<br> 120 WorkerPid = spawn_link(<br> 121 fun() -><br> 122<br> 123 eep0018:start_driver(code:priv_dir(fast_json)),<br>
124<br> 125 JsonTerm = eep0018:json_to_term(JsonTextBin),<br> 126<br> 127 CallerPid ! {self(), JsonTerm}<br> 128 end),<br> 129<br> 130 JsonTerm = receive {WorkerPid, T} -> T end,<br>
131<br> 132 %% TODO: json_to_term does not currently return the 'left over' tail.<br> 133<br> 134 {ok, JsonTerm, []}.<br> <br><br>The erlang code in the driver looks like:<br><br>json_to_term(Json) when is_binary(Json) -><br>
% The null byte is important for bare literals. Without it<br> % yajl will throw a fit because it doesn't think it's finished<br> % parsing correctly.<br> [] = erlang:port_control(drv_port(), 1, <<Json/binary, 0:8>>),<br>
receive<br> Term -><br> Term<br> end.<br><br> start_driver(LibDir) -><br> case erl_ddll:load_driver(LibDir, "eep0018_drv") of<br> ok -><br> ok;<br> {error, already_loaded} -><br>
ok;<br> %ok = erl_ddll:reload_driver(LibDir, "eep0018_drv");<br> {error, Error} -><br> exit(erl_ddll:format_error(Error))<br> end.<br><br>drv_port() -><br> case get(eep0018_drv_port) of<br>
undefined -><br> Port = open_port({spawn, "eep0018_drv"}, [binary]),<br> put(eep0018_drv_port, Port),<br> Port;<br> Port -><br> Port<br> end.<br><br><br>Here's more details about the OS/compiler on which the problem occurs.<br>
<br>% cat /etc/redhat-release<br>
Red Hat Enterprise Linux Client release 5.1 (Tikanga)<br>
<br>
% gcc -v<br>
Using built-in specs.<br>
Target: x86_64-redhat-linux<br>
Configured with: ../configure --prefix=/usr --mandir=/usr/share/man
--infodir=/usr/share/info --enable-shared --enable-threads=posix
--enable-checking=release --with-system-zlib --enable-__cxa_atexit
--disable-libunwind-exceptions --enable-libgcj-multifile
--enable-languages=c,c++,objc,obj-c++,java,fortran,ada
--enable-java-awt=gtk --disable-dssi --enable-plugin
--with-java-home=/usr/lib/jvm/java-1.4.2-gcj-1.4.2.0/jre
--with-cpu=generic --host=x86_64-redhat-linux<br>
Thread model: posix<br>
gcc version 4.1.2 20070626 (Red Hat 4.1.2-14)<br>
<br>
Kernel:<br><br>% uname -a<br>Linux 2.6.18-53.1.14.el5 #1 SMP Tue Feb 19 07:18:46 EST 2008 x86_64 x86_64 x86_64 GNU/Linux<br><br>