From ba8740af39b7d4c612b2ee55e3bad6fbdcaf1418 Mon Sep 17 00:00:00 2001 From: Steve Vinoski Date: Mon, 10 Aug 2015 08:34:28 -0400 Subject: Handle ERRNO_BLOCK in fd_driver async functions Several users on erlang-questions have reported problems with recent releases where output to standard_error causes standard_error_sup to die from receiving an unexpected eagain error. In the fd_driver, change the fd_async() function to handle EINTR, and change fd_ready_async() to handle ERRNO_BLOCK. Add a new test to standard_error_SUITE to generate output to standard_error and ensure that standard_error_sup does not die. Thanks to Kota Uenishi for contributing the test case. --- erts/emulator/sys/unix/sys.c | 16 ++++++++++++---- lib/kernel/test/standard_error_SUITE.erl | 31 +++++++++++++++++++++++++++++-- 2 files changed, 41 insertions(+), 6 deletions(-) diff --git a/erts/emulator/sys/unix/sys.c b/erts/emulator/sys/unix/sys.c index b036b20b7b..8d7da3e47e 100644 --- a/erts/emulator/sys/unix/sys.c +++ b/erts/emulator/sys/unix/sys.c @@ -2527,7 +2527,7 @@ fd_async(void *async_data) SysIOVec *iov0; SysIOVec *iov; int iovlen; - int err; + int err = 0; /* much of this code is stolen from efile_drv:invoke_writev */ driver_pdl_lock(dd->blocking->pdl); iov0 = driver_peekq(dd->port_num, &iovlen); @@ -2542,8 +2542,11 @@ fd_async(void *async_data) memcpy(iov,iov0,iovlen*sizeof(SysIOVec)); driver_pdl_unlock(dd->blocking->pdl); - res = writev(dd->ofd, iov, iovlen); - err = errno; + do { + res = writev(dd->ofd, iov, iovlen); + } while (res < 0 && errno == EINTR); + if (res < 0) + err = errno; erts_free(ERTS_ALC_T_SYS_WRITE_BUF, iov); } @@ -2582,7 +2585,12 @@ void fd_ready_async(ErlDrvData drv_data, return /* 0; */; } } else if (dd->blocking->res < 0) { - driver_failure_posix(port_num, dd->blocking->err); + if (dd->blocking->err == ERRNO_BLOCK) { + set_busy_port(port_num, 1); + /* still data left to write in queue */ + driver_async(port_num, &dd->blocking->pkey, fd_async, dd, NULL); + } else + driver_failure_posix(port_num, dd->blocking->err); return; /* -1; */ } return; /* 0; */ diff --git a/lib/kernel/test/standard_error_SUITE.erl b/lib/kernel/test/standard_error_SUITE.erl index e8917bbd47..97ead9b9fd 100644 --- a/lib/kernel/test/standard_error_SUITE.erl +++ b/lib/kernel/test/standard_error_SUITE.erl @@ -21,13 +21,13 @@ -module(standard_error_SUITE). -export([all/0,suite/0]). --export([badarg/1,getopts/1]). +-export([badarg/1,getopts/1,output/1]). suite() -> [{ct_hooks,[ts_install_cth]}]. all() -> - [badarg,getopts]. + [badarg,getopts,output]. badarg(Config) when is_list(Config) -> {'EXIT',{badarg,_}} = (catch io:put_chars(standard_error, [oops])), @@ -37,3 +37,30 @@ badarg(Config) when is_list(Config) -> getopts(Config) when is_list(Config) -> [{encoding,latin1}] = io:getopts(standard_error), ok. + +%% Test that writing a lot of output to standard_error does not cause the +%% processes handling it to terminate like this: +%% +%% =ERROR REPORT==== 9-Aug-2015::23:19:23 === +%% ** Generic server standard_error_sup terminating +%% ** Last message in was {'EXIT',<0.28.0>,eagain} +%% ** When Server state == {state,standard_error,undefined,<0.28.0>, +%% {local,standard_error_sup}} +%% ** Reason for termination == +%% ** eagain +%% +%% This problem, observed with Erlang 18.0.2, was fixed in fd_driver by +%% properly handling EAGAIN if it arises on file descriptor writes. +%% +output(Config) when is_list(Config) -> + Ref = monitor(process, standard_error_sup), + Chars = [ [["1234567890" || _ <- lists:seq(1,10)], $\s, + integer_to_list(L), $\r, $\n] || L <- lists:seq(1, 100) ], + ok = io:put_chars(standard_error, Chars), + receive + {'DOWN', Ref, process, _, _} -> + error(standard_error_noproc) + after + 500 -> + ok + end. -- cgit v1.2.3