patch rfc: PR28661: debuginfod thread-pool
Commit Message
Hi -
While I think this patch itself is fine, and works around the
libmicrohttpd bug that motivated it, I don't know how to test it
seriously in the testsuite. (We can certainly try few -C options for
parsing & operability.) The error edge cases only appear to occur
under very high load and task limits such as those imposed by systemd
cgroups.
Author: Frank Ch. Eigler <fche@redhat.com>
Date: Wed Dec 8 22:41:47 2021 -0500
PR28661: debuginfo connection thread pool support
Add an option -C, which activates libmicrohttpd's thread-pool mode for
handling incoming http connections. Add libmicrohttpd error-logging
callback function so as to receive indication of its internal errors,
and relay counts to our metrics. Some of these internal errors tipped
us off to a microhttpd bug that thread pooling works around. Document
in debuginfod.8 page. Hand-tested against "ulimit -u NNN" shells.
Signed-off-by: Frank Ch. Eigler <fche@redhat.com>
Comments
Hi Frank,
On Wed, 2021-12-08 at 22:55 -0500, Frank Ch. Eigler via Elfutils-devel
wrote:
> While I think this patch itself is fine, and works around the
> libmicrohttpd bug that motivated it, I don't know how to test it
> seriously in the testsuite. (We can certainly try few -C options for
> parsing & operability.) The error edge cases only appear to occur
> under very high load and task limits such as those imposed by systemd
> cgroups.
We have a couple of tests that try to seek the limit that they can
still safely run under (e.g. run-large-elf-file.sh), but they were
probably mistakes to include in the normal regression test suite. It is
tricky to find the appropriate limit on a machine without hitting it
and causing the test machine to fall over (briefly).
If you can use ulimit -u or ulimit -T in the run-test.sh script then
please use that, but that probably requires launching sub-shells and
you quickly end up in shell-hell.
So I would recommend to simply add a testcase that just uses no-option,
-C and -C 256 (or take any arbitrary number, 1 might be an interesting
corner case) and see that if you have 4 (8, 16, ...?) debuginfod-find
(or curl metric) processes doing some parallel queries works as
expected.
> Author: Frank Ch. Eigler <fche@redhat.com>
> Date: Wed Dec 8 22:41:47 2021 -0500
>
> PR28661: debuginfo connection thread pool support
>
> Add an option -C, which activates libmicrohttpd's thread-pool mode for
> handling incoming http connections. Add libmicrohttpd error-logging
> callback function so as to receive indication of its internal errors,
> and relay counts to our metrics. Some of these internal errors tipped
> us off to a microhttpd bug that thread pooling works around. Document
> in debuginfod.8 page. Hand-tested against "ulimit -u NNN" shells.
>
> Signed-off-by: Frank Ch. Eigler <fche@redhat.com>
>
> diff --git a/debuginfod/ChangeLog b/debuginfod/ChangeLog
> index 21d0721ef080..125e7d816f51 100644
> --- a/debuginfod/ChangeLog
> +++ b/debuginfod/ChangeLog
> @@ -1,3 +1,11 @@
> +2021-12-08 Frank Ch. Eigler <fche@redhat.com>
> +
> + * debuginfod.cxx (connection_pool): New global.
> + (parse_opt): Parse & check -C option to set it.
> + (error_cb): New callback for libmicrohttpd error counting.
> + (main): Activate MHD_OPTION_THREAD_POOL_SIZE if appropriate.
> + Activate error_cb.
> +
> 2021-12-01 Mark Wielaard <mark@klomp.org>
>
> * debuginfod-client.c (debuginfod_query_server): Free tmp_url on
> diff --git a/debuginfod/debuginfod.cxx b/debuginfod/debuginfod.cxx
> index 0d3f02978ee2..bb0c6cd65670 100644
> --- a/debuginfod/debuginfod.cxx
> +++ b/debuginfod/debuginfod.cxx
> @@ -352,7 +352,9 @@ static const struct argp_option options[] =
> { "rescan-time", 't', "SECONDS", 0, "Number of seconds to wait between rescans, 0=disable.", 0 },
> { "groom-time", 'g', "SECONDS", 0, "Number of seconds to wait between database grooming, 0=disable.", 0 },
> { "maxigroom", 'G', NULL, 0, "Run a complete database groom/shrink pass at startup.", 0 },
> - { "concurrency", 'c', "NUM", 0, "Limit scanning thread concurrency to NUM.", 0 },
> + { "concurrency", 'c', "NUM", 0, "Limit scanning thread concurrency to NUM, default=#CPUs.", 0 },
> + { "connection-pool", 'C', "NUM", OPTION_ARG_OPTIONAL,
> + "Use webapi connection pool with NUM threads, default=unlim.", 0 },
> { "include", 'I', "REGEX", 0, "Include files matching REGEX, default=all.", 0 },
> { "exclude", 'X', "REGEX", 0, "Exclude files matching REGEX, default=none.", 0 },
> { "port", 'p', "NUM", 0, "HTTP port to listen on, default 8002.", 0 },
> @@ -411,6 +413,7 @@ static unsigned rescan_s = 300;
> static unsigned groom_s = 86400;
> static bool maxigroom = false;
> static unsigned concurrency = std::thread::hardware_concurrency() ?: 1;
> +static int connection_pool = 0;
> static set<string> source_paths;
> static bool scan_files = false;
> static map<string,string> scan_archives;
> @@ -557,6 +560,16 @@ parse_opt (int key, char *arg,
> concurrency = (unsigned) atoi(arg);
> if (concurrency < 1) concurrency = 1;
> break;
> + case 'C':
> + if (arg)
> + {
> + connection_pool = atoi(arg);
> + if (connection_pool < 2)
> + argp_failure(state, 1, EINVAL, "-C NUM minimum 2");
> + }
> + else // arg not given
> + connection_pool = std::thread::hardware_concurrency() * 2 ?: 2;
> + break;
Aha, forget about my -C 1 corner case above then :)
> case 'I':
> // NB: no problem with unconditional free here - an earlier failed regcomp would exit program
> if (passive_p)
> @@ -3684,7 +3698,13 @@ sigusr2_handler (int /* sig */)
> }
>
>
> -
> +static void // error logging callback from libmicrohttpd internals
> +error_cb (void *arg, const char *fmt, va_list ap)
> +{
> + (void) arg;
> + inc_metric("error_count","libmicrohttpd",fmt);
> + (void) vdprintf (STDERR_FILENO, fmt, ap);
> +}
>
>
> // A user-defined sqlite function, to score the sharedness of the
> @@ -3829,7 +3849,7 @@ main (int argc, char *argv[])
>
> // Start httpd server threads. Separate pool for IPv4 and IPv6, in
> // case the host only has one protocol stack.
> - MHD_Daemon *d4 = MHD_start_daemon (MHD_USE_THREAD_PER_CONNECTION
> + MHD_Daemon *d4 = MHD_start_daemon ((connection_pool ? 0 : MHD_USE_THREAD_PER_CONNECTION)
> #if MHD_VERSION >= 0x00095300
> | MHD_USE_INTERNAL_POLLING_THREAD
> #else
> @@ -3839,8 +3859,11 @@ main (int argc, char *argv[])
> http_port,
> NULL, NULL, /* default accept policy */
> handler_cb, NULL, /* handler callback */
> + MHD_OPTION_EXTERNAL_LOGGER, error_cb, NULL,
> + (connection_pool ? MHD_OPTION_THREAD_POOL_SIZE : MHD_OPTION_END),
> + (connection_pool ? (int)connection_pool : MHD_OPTION_END),
> MHD_OPTION_END);
> - MHD_Daemon *d6 = MHD_start_daemon (MHD_USE_THREAD_PER_CONNECTION
> + MHD_Daemon *d6 = MHD_start_daemon ((connection_pool ? 0 : MHD_USE_THREAD_PER_CONNECTION)
> #if MHD_VERSION >= 0x00095300
> | MHD_USE_INTERNAL_POLLING_THREAD
> #else
> @@ -3851,6 +3874,9 @@ main (int argc, char *argv[])
> http_port,
> NULL, NULL, /* default accept policy */
> handler_cb, NULL, /* handler callback */
> + MHD_OPTION_EXTERNAL_LOGGER, error_cb, NULL,
> + (connection_pool ? MHD_OPTION_THREAD_POOL_SIZE : MHD_OPTION_END),
> + (connection_pool ? (int)connection_pool : MHD_OPTION_END),
> MHD_OPTION_END);
Urgh, the use of varargs in MHD_start_daemon makes my head hurt. But it
does look correct.
> if (d4 == NULL && d6 == NULL) // neither ipv4 nor ipv6? boo
> @@ -3904,6 +3930,8 @@ main (int argc, char *argv[])
>
> if (! passive_p)
> obatched(clog) << "search concurrency " << concurrency << endl;
> + obatched(clog) << "webapi connection pool " << connection_pool
> + << (connection_pool ? "" : " (unlimited)") << endl;
> if (! passive_p)
> obatched(clog) << "rescan time " << rescan_s << endl;
> obatched(clog) << "fdcache fds " << fdcache_fds << endl;
> diff --git a/doc/ChangeLog b/doc/ChangeLog
> index 7a73fa107bf3..f25bcd2ee2b3 100644
> --- a/doc/ChangeLog
> +++ b/doc/ChangeLog
> @@ -1,3 +1,8 @@
> +2021-12-08 Frank Ch. Eigler <fche@redhat.com>
> +
> + PR28661
> + * debuginfod.8 (-C): Document new flag.
> +
> 2021-11-05 Frank Ch. Eigler <fche@redhat.com>
>
> PR28430
> diff --git a/doc/debuginfod.8 b/doc/debuginfod.8
> index 1e56f6568322..ee8e4078e5b5 100644
> --- a/doc/debuginfod.8
> +++ b/doc/debuginfod.8
> @@ -205,6 +205,23 @@ This important for controlling CPU-intensive operations like parsing
> an ELF file and especially decompressing archives. The default is the
> number of processors on the system; the minimum is 1.
>
> +.TP
> +.B "\-C" "\-C=NUM" "\-\-connection\-pool" "\-\-connection\-pool=NUM"
> +Set the size of the pool of threads serving webapi queries. The
> +following table summarizes the interpretaton of this option and its
> +optional NUM parameter.
> +.TS
> +l l.
> +no option clone new thread for every request, no fixed pool
> +\-C use a fixed thread pool sized automatically
> +\-C=NUM use a fixed thread pool sized NUM, minimum 2
> +.TE
> +
> +The first mode is useful for friendly bursty traffic. The second mode
> +is a simple and safe configuration based on the number of processors.
> +The third mode is suitable for tuned load-limiting configurations
> +facing unruly traffic.
Thanks, the documentation looks pretty clear.
Cheers,
Mark
Hi -
> [...]
> If you can use ulimit -u or ulimit -T in the run-test.sh script then
> please use that, but that probably requires launching sub-shells and
> you quickly end up in shell-hell.
A problem I found with that is that ulimit -u appears to be systemwide
in the sense that a new process/thread will be prevented if the total
systemwide processes of that user exceed this number. It's not just
for accounting that particular processes' own children. (ulimit -T
doesn't work on my f35 machine with bash or zsh or csh.)
> So I would recommend to simply add a testcase that just uses no-option,
> -C and -C 256 (or take any arbitrary number, 1 might be an interesting
> corner case) and see that if you have 4 (8, 16, ...?) debuginfod-find
> (or curl metric) processes doing some parallel queries works as
> expected.
Yeah, I can/will do that. Well, for any of these -C settings, even
thousands of concurrently issued curl jobs should succeed, just not
quite as quickly.
- FChE
Hi, Mark -
> So I would recommend to simply add a testcase that just uses no-option,
> -C and -C 256 (or take any arbitrary number, 1 might be an interesting
> corner case) and see that if you have 4 (8, 16, ...?) debuginfod-find
> (or curl metric) processes doing some parallel queries works as
> expected.
OK, here's the current version, with a test, and with one more small
improvement to the error message printer (to add timestamp & batching).
Author: Frank Ch. Eigler <fche@redhat.com>
Date: Wed Dec 8 22:41:47 2021 -0500
PR28661: debuginfo connection thread pool support
Add an option -C, which activates libmicrohttpd's thread-pool mode for
handling incoming http connections. Add libmicrohttpd error-logging
callback function so as to receive indication of its internal errors,
and relay counts to our metrics. Some of these internal errors tipped
us off to a microhttpd bug that thread pooling works around. Document
in debuginfod.8 page. Hand-tested against "ulimit -u NNN" shells, and
with a less strenuous new test case.
Signed-off-by: Frank Ch. Eigler <fche@redhat.com>
diff --git a/NEWS b/NEWS
index 490932ae4ef9..6be58866f100 100644
--- a/NEWS
+++ b/NEWS
@@ -1,3 +1,8 @@
+Version 0.187 after 0.186
+
+debuginfod: Support -C option for connection thread pooling.
+
+
Version 0.186
debuginfod-client: Default $DEBUGINFOD_URLS is computed from drop-in files
diff --git a/debuginfod/ChangeLog b/debuginfod/ChangeLog
index df373201d5c6..2642ef5eeaf1 100644
--- a/debuginfod/ChangeLog
+++ b/debuginfod/ChangeLog
@@ -3,6 +3,14 @@
* debuginfod.cxx (database_stats_report): Don't format clog
using 'right' and 'setw(20)'.
+2021-12-08 Frank Ch. Eigler <fche@redhat.com>
+
+ * debuginfod.cxx (connection_pool): New global.
+ (parse_opt): Parse & check -C option to set it.
+ (error_cb): New callback for libmicrohttpd error counting.
+ (main): Activate MHD_OPTION_THREAD_POOL_SIZE if appropriate.
+ Activate error_cb.
+
2021-12-04 Mark Wielaard <mark@klomp.org>
* debuginfod.cxx (main): Call debuginfod_pool_groom before exit.
diff --git a/debuginfod/debuginfod.cxx b/debuginfod/debuginfod.cxx
index 887e4f5abd44..bb8e8e102896 100644
--- a/debuginfod/debuginfod.cxx
+++ b/debuginfod/debuginfod.cxx
@@ -353,7 +353,9 @@ static const struct argp_option options[] =
{ "rescan-time", 't', "SECONDS", 0, "Number of seconds to wait between rescans, 0=disable.", 0 },
{ "groom-time", 'g', "SECONDS", 0, "Number of seconds to wait between database grooming, 0=disable.", 0 },
{ "maxigroom", 'G', NULL, 0, "Run a complete database groom/shrink pass at startup.", 0 },
- { "concurrency", 'c', "NUM", 0, "Limit scanning thread concurrency to NUM.", 0 },
+ { "concurrency", 'c', "NUM", 0, "Limit scanning thread concurrency to NUM, default=#CPUs.", 0 },
+ { "connection-pool", 'C', "NUM", OPTION_ARG_OPTIONAL,
+ "Use webapi connection pool with NUM threads, default=unlim.", 0 },
{ "include", 'I', "REGEX", 0, "Include files matching REGEX, default=all.", 0 },
{ "exclude", 'X', "REGEX", 0, "Exclude files matching REGEX, default=none.", 0 },
{ "port", 'p', "NUM", 0, "HTTP port to listen on, default 8002.", 0 },
@@ -412,6 +414,7 @@ static unsigned rescan_s = 300;
static unsigned groom_s = 86400;
static bool maxigroom = false;
static unsigned concurrency = std::thread::hardware_concurrency() ?: 1;
+static int connection_pool = 0;
static set<string> source_paths;
static bool scan_files = false;
static map<string,string> scan_archives;
@@ -558,6 +561,16 @@ parse_opt (int key, char *arg,
concurrency = (unsigned) atoi(arg);
if (concurrency < 1) concurrency = 1;
break;
+ case 'C':
+ if (arg)
+ {
+ connection_pool = atoi(arg);
+ if (connection_pool < 2)
+ argp_failure(state, 1, EINVAL, "-C NUM minimum 2");
+ }
+ else // arg not given
+ connection_pool = std::thread::hardware_concurrency() * 2 ?: 2;
+ break;
case 'I':
// NB: no problem with unconditional free here - an earlier failed regcomp would exit program
if (passive_p)
@@ -1368,6 +1381,7 @@ class libarchive_fdcache
if (verbose > 3)
obatched(clog) << "fdcache interned a=" << a << " b=" << b
<< " fd=" << fd << " mb=" << mb << " front=" << front_p << endl;
+
set_metrics();
}
@@ -3708,7 +3722,15 @@ sigusr2_handler (int /* sig */)
}
-
+static void // error logging callback from libmicrohttpd internals
+error_cb (void *arg, const char *fmt, va_list ap)
+{
+ (void) arg;
+ inc_metric("error_count","libmicrohttpd",fmt);
+ char errmsg[512];
+ (void) vsnprintf (errmsg, sizeof(errmsg), fmt, ap); // ok if slightly truncated
+ obatched(cerr) << "libmicrohttpd error: " << errmsg; // MHD_DLOG calls already include \n
+}
// A user-defined sqlite function, to score the sharedness of the
@@ -3853,7 +3875,7 @@ main (int argc, char *argv[])
// Start httpd server threads. Separate pool for IPv4 and IPv6, in
// case the host only has one protocol stack.
- MHD_Daemon *d4 = MHD_start_daemon (MHD_USE_THREAD_PER_CONNECTION
+ MHD_Daemon *d4 = MHD_start_daemon ((connection_pool ? 0 : MHD_USE_THREAD_PER_CONNECTION)
#if MHD_VERSION >= 0x00095300
| MHD_USE_INTERNAL_POLLING_THREAD
#else
@@ -3863,8 +3885,11 @@ main (int argc, char *argv[])
http_port,
NULL, NULL, /* default accept policy */
handler_cb, NULL, /* handler callback */
+ MHD_OPTION_EXTERNAL_LOGGER, error_cb, NULL,
+ (connection_pool ? MHD_OPTION_THREAD_POOL_SIZE : MHD_OPTION_END),
+ (connection_pool ? (int)connection_pool : MHD_OPTION_END),
MHD_OPTION_END);
- MHD_Daemon *d6 = MHD_start_daemon (MHD_USE_THREAD_PER_CONNECTION
+ MHD_Daemon *d6 = MHD_start_daemon ((connection_pool ? 0 : MHD_USE_THREAD_PER_CONNECTION)
#if MHD_VERSION >= 0x00095300
| MHD_USE_INTERNAL_POLLING_THREAD
#else
@@ -3875,6 +3900,9 @@ main (int argc, char *argv[])
http_port,
NULL, NULL, /* default accept policy */
handler_cb, NULL, /* handler callback */
+ MHD_OPTION_EXTERNAL_LOGGER, error_cb, NULL,
+ (connection_pool ? MHD_OPTION_THREAD_POOL_SIZE : MHD_OPTION_END),
+ (connection_pool ? (int)connection_pool : MHD_OPTION_END),
MHD_OPTION_END);
if (d4 == NULL && d6 == NULL) // neither ipv4 nor ipv6? boo
@@ -3928,6 +3956,8 @@ main (int argc, char *argv[])
if (! passive_p)
obatched(clog) << "search concurrency " << concurrency << endl;
+ obatched(clog) << "webapi connection pool " << connection_pool
+ << (connection_pool ? "" : " (unlimited)") << endl;
if (! passive_p)
obatched(clog) << "rescan time " << rescan_s << endl;
obatched(clog) << "fdcache fds " << fdcache_fds << endl;
diff --git a/doc/ChangeLog b/doc/ChangeLog
index 7a73fa107bf3..f25bcd2ee2b3 100644
--- a/doc/ChangeLog
+++ b/doc/ChangeLog
@@ -1,3 +1,8 @@
+2021-12-08 Frank Ch. Eigler <fche@redhat.com>
+
+ PR28661
+ * debuginfod.8 (-C): Document new flag.
+
2021-11-05 Frank Ch. Eigler <fche@redhat.com>
PR28430
diff --git a/doc/debuginfod.8 b/doc/debuginfod.8
index 1e56f6568322..ee8e4078e5b5 100644
--- a/doc/debuginfod.8
+++ b/doc/debuginfod.8
@@ -205,6 +205,23 @@ This important for controlling CPU-intensive operations like parsing
an ELF file and especially decompressing archives. The default is the
number of processors on the system; the minimum is 1.
+.TP
+.B "\-C" "\-C=NUM" "\-\-connection\-pool" "\-\-connection\-pool=NUM"
+Set the size of the pool of threads serving webapi queries. The
+following table summarizes the interpretaton of this option and its
+optional NUM parameter.
+.TS
+l l.
+no option clone new thread for every request, no fixed pool
+\-C use a fixed thread pool sized automatically
+\-C=NUM use a fixed thread pool sized NUM, minimum 2
+.TE
+
+The first mode is useful for friendly bursty traffic. The second mode
+is a simple and safe configuration based on the number of processors.
+The third mode is suitable for tuned load-limiting configurations
+facing unruly traffic.
+
.TP
.B "\-L"
Traverse symbolic links encountered during traversal of the PATHs,
diff --git a/tests/ChangeLog b/tests/ChangeLog
index 76cb974a43c1..82061c6e9a58 100644
--- a/tests/ChangeLog
+++ b/tests/ChangeLog
@@ -1,3 +1,9 @@
+2021-12-09 Frank Ch. Eigler <fche@redhat.com>
+
+ * debuginfod-subr.sh (xfail): New proc.
+ * run-debuginfod-webapi-concurrency.sh: New test for -C.
+ * Makefile.am: List it.
+
2021-12-04 Mark Wielaard <mark@klomp.org>
* Makefile.am (EXTRA_NLIST_CFLAGS): New variable depends on
diff --git a/tests/Makefile.am b/tests/Makefile.am
index 8acaeaf2a3a6..b2da2c83e15a 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -242,7 +242,8 @@ TESTS += run-debuginfod-dlopen.sh \
run-debuginfod-percent-escape.sh \
run-debuginfod-x-forwarded-for.sh \
run-debuginfod-response-headers.sh \
- run-debuginfod-extraction-passive.sh
+ run-debuginfod-extraction-passive.sh \
+ run-debuginfod-webapi-concurrency.sh
endif
endif
@@ -539,6 +540,7 @@ EXTRA_DIST = run-arextract.sh run-arsymtest.sh run-ar.sh \
run-debuginfod-percent-escape.sh \
run-debuginfod-response-headers.sh \
run-debuginfod-extraction-passive.sh \
+ run-debuginfod-webapi-concurrency.sh \
debuginfod-rpms/fedora30/hello2-1.0-2.src.rpm \
debuginfod-rpms/fedora30/hello2-1.0-2.x86_64.rpm \
debuginfod-rpms/fedora30/hello2-debuginfo-1.0-2.x86_64.rpm \
diff --git a/tests/debuginfod-subr.sh b/tests/debuginfod-subr.sh
index 59033f35980e..0b59b5b87e55 100755
--- a/tests/debuginfod-subr.sh
+++ b/tests/debuginfod-subr.sh
@@ -158,3 +158,13 @@ PORT1=0
PORT2=0
PID1=0
PID2=0
+
+
+# run $1 as a sh -c command, invert result code
+xfail() {
+ if sh -c "$1"; then
+ false
+ else
+ true
+ fi
+}
diff --git a/tests/run-debuginfod-webapi-concurrency.sh b/tests/run-debuginfod-webapi-concurrency.sh
new file mode 100755
index 000000000000..513f834f40d5
--- /dev/null
+++ b/tests/run-debuginfod-webapi-concurrency.sh
@@ -0,0 +1,60 @@
+#!/usr/bin/env bash
+#
+# Copyright (C) 2021 Red Hat, Inc.
+# This file is part of elfutils.
+#
+# This file is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# elfutils is distributed in the hope that it will be useful, but
+# WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+
+. $srcdir/debuginfod-subr.sh
+
+# for test case debugging, uncomment:
+set -x
+
+mkdir Z
+# This variable is essential and ensures no time-race for claiming ports occurs
+# set base to a unique multiple of 100 not used in any other 'run-debuginfod-*' test
+base=12000
+get_ports
+
+export DEBUGINFOD_CACHE_PATH=${PWD}/.client_cache
+
+cp -rvp ${abs_srcdir}/debuginfod-tars Z
+tempfiles Z
+
+
+for Cnum in "" "-C" "-C10" "-C100"
+do
+ env LD_LIBRARY_PATH=$ldpath ${abs_builddir}/../debuginfod/debuginfod $VERBOSE "$Cnum" -d :memory: -Z .tar.xz -Z .tar.bz2=bzcat -p $PORT1 -t0 -g0 -v --fdcache-fds=0 --fdcache-prefetch-fds=0 Z >> vlog$PORT1 2>&1 &
+ PID1=$!
+ tempfiles vlog$PORT1
+ errfiles vlog$PORT1
+
+ wait_ready $PORT1 'ready' 1
+ # Wait for server to finish indexing
+ wait_ready $PORT1 'thread_work_total{role="traverse"}' 1
+ wait_ready $PORT1 'thread_work_pending{role="scan"}' 0
+ wait_ready $PORT1 'thread_busy{role="scan"}' 0
+
+ # Do a bunch of lookups in parallel
+ for jobs in `seq 400`; do
+ curl -s http://localhost:$PORT1/buildid/cee13b2ea505a7f37bd20d271c6bc7e5f8d2dfcb/debuginfo > /dev/null &
+ done
+ (sleep 5; curl -s http://localhost:$PORT1/metrics | egrep 'error|transfers'; kill $PID1) &
+ wait
+ PID1=0
+done
+
+xfail "grep Server.reached.connection vlog$PORT1" # PR18661
+
+exit 0
Hi Frank,
On Thu, 2021-12-09 at 19:10 -0500, Frank Ch. Eigler via Elfutils-devel
wrote:
> So I would recommend to simply add a testcase that just uses no-
> > option,
> > -C and -C 256 (or take any arbitrary number, 1 might be an interesting
> > corner case) and see that if you have 4 (8, 16, ...?) debuginfod-find
> > (or curl metric) processes doing some parallel queries works as
> > expected.
>
> OK, here's the current version, with a test, and with one more small
> improvement to the error message printer (to add timestamp & batching).
Looks good, but two nitpicks.
> -
> +static void // error logging callback from libmicrohttpd internals
> +error_cb (void *arg, const char *fmt, va_list ap)
> +{
> + (void) arg;
> + inc_metric("error_count","libmicrohttpd",fmt);
> + char errmsg[512];
> + (void) vsnprintf (errmsg, sizeof(errmsg), fmt, ap); // ok if slightly truncated
> + obatched(cerr) << "libmicrohttpd error: " << errmsg; // MHD_DLOG calls already include \n
> +}
That vsnprintf and truncation comment had me scared for a minute.
But vsnprintf always terminates the string with a '\0' so that should
be fine.
diff --git a/tests/ChangeLog b/tests/ChangeLog
> diff --git a/tests/debuginfod-subr.sh b/tests/debuginfod-subr.sh
> index 59033f35980e..0b59b5b87e55 100755
> --- a/tests/debuginfod-subr.sh
> +++ b/tests/debuginfod-subr.sh
> @@ -158,3 +158,13 @@ PORT1=0
> PORT2=0
> PID1=0
> PID2=0
> +
> +
> +# run $1 as a sh -c command, invert result code
> +xfail() {
> + if sh -c "$1"; then
> + false
> + else
> + true
> + fi
> +}
Aha, nice. We should use that in other tests too.
> diff --git a/tests/run-debuginfod-webapi-concurrency.sh b/tests/run-
> debuginfod-webapi-concurrency.sh
> new file mode 100755
> index 000000000000..513f834f40d5
> --- /dev/null
> +++ b/tests/run-debuginfod-webapi-concurrency.sh
> @@ -0,0 +1,60 @@
> +#!/usr/bin/env bash
> +#
> +# Copyright (C) 2021 Red Hat, Inc.
> +# This file is part of elfutils.
> +#
> +# This file is free software; you can redistribute it and/or modify
> +# it under the terms of the GNU General Public License as published
> by
> +# the Free Software Foundation; either version 3 of the License, or
> +# (at your option) any later version.
> +#
> +# elfutils is distributed in the hope that it will be useful, but
> +# WITHOUT ANY WARRANTY; without even the implied warranty of
> +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> +# GNU General Public License for more details.
> +#
> +# You should have received a copy of the GNU General Public License
> +# along with this program. If not, see <
> http://www.gnu.org/licenses/>.
> +
> +. $srcdir/debuginfod-subr.sh
> +
> +# for test case debugging, uncomment:
> +set -x
> +
> +mkdir Z
> +# This variable is essential and ensures no time-race for claiming
> ports occurs
> +# set base to a unique multiple of 100 not used in any other 'run-
> debuginfod-*' test
> +base=12000
> +get_ports
> +
> +export DEBUGINFOD_CACHE_PATH=${PWD}/.client_cache
> +
> +cp -rvp ${abs_srcdir}/debuginfod-tars Z
> +tempfiles Z
> +
> +
> +for Cnum in "" "-C" "-C10" "-C100"
> +do
> + env LD_LIBRARY_PATH=$ldpath
> ${abs_builddir}/../debuginfod/debuginfod $VERBOSE "$Cnum" -d :memory:
> -Z .tar.xz -Z .tar.bz2=bzcat -p $PORT1 -t0 -g0 -v --fdcache-fds=0 --
> fdcache-prefetch-fds=0 Z >> vlog$PORT1 2>&1 &
> + PID1=$!
> + tempfiles vlog$PORT1
> + errfiles vlog$PORT1
> +
> + wait_ready $PORT1 'ready' 1
> + # Wait for server to finish indexing
> + wait_ready $PORT1 'thread_work_total{role="traverse"}' 1
> + wait_ready $PORT1 'thread_work_pending{role="scan"}' 0
> + wait_ready $PORT1 'thread_busy{role="scan"}' 0
> +
> + # Do a bunch of lookups in parallel
> + for jobs in `seq 400`; do
> + curl -s
> http://localhost:$PORT1/buildid/cee13b2ea505a7f37bd20d271c6bc7e5f8d2dfcb/debuginfo
> > /dev/null &
> + done
> + (sleep 5; curl -s http://localhost:$PORT1/metrics | egrep
> 'error|transfers'; kill $PID1) &
> + wait
> + PID1=0
> +done
Launching 400 processes at once seems a lot. But maybe machines these
days are fine with that. I would say that 50 should also do the trick.
But maybe I just have wimpy machines :)
Is there a more elegant way to check all requests have been processed
than a sleep 5 followed by a metric scrape for errors? Is there a
metric that gives the number of successful queries that we could use
instead with wait_ready?
> +xfail "grep Server.reached.connection vlog$PORT1" # PR18661
> +
> +exit 0
Cheers,
Mark
@@ -1,3 +1,11 @@
+2021-12-08 Frank Ch. Eigler <fche@redhat.com>
+
+ * debuginfod.cxx (connection_pool): New global.
+ (parse_opt): Parse & check -C option to set it.
+ (error_cb): New callback for libmicrohttpd error counting.
+ (main): Activate MHD_OPTION_THREAD_POOL_SIZE if appropriate.
+ Activate error_cb.
+
2021-12-01 Mark Wielaard <mark@klomp.org>
* debuginfod-client.c (debuginfod_query_server): Free tmp_url on
@@ -352,7 +352,9 @@ static const struct argp_option options[] =
{ "rescan-time", 't', "SECONDS", 0, "Number of seconds to wait between rescans, 0=disable.", 0 },
{ "groom-time", 'g', "SECONDS", 0, "Number of seconds to wait between database grooming, 0=disable.", 0 },
{ "maxigroom", 'G', NULL, 0, "Run a complete database groom/shrink pass at startup.", 0 },
- { "concurrency", 'c', "NUM", 0, "Limit scanning thread concurrency to NUM.", 0 },
+ { "concurrency", 'c', "NUM", 0, "Limit scanning thread concurrency to NUM, default=#CPUs.", 0 },
+ { "connection-pool", 'C', "NUM", OPTION_ARG_OPTIONAL,
+ "Use webapi connection pool with NUM threads, default=unlim.", 0 },
{ "include", 'I', "REGEX", 0, "Include files matching REGEX, default=all.", 0 },
{ "exclude", 'X', "REGEX", 0, "Exclude files matching REGEX, default=none.", 0 },
{ "port", 'p', "NUM", 0, "HTTP port to listen on, default 8002.", 0 },
@@ -411,6 +413,7 @@ static unsigned rescan_s = 300;
static unsigned groom_s = 86400;
static bool maxigroom = false;
static unsigned concurrency = std::thread::hardware_concurrency() ?: 1;
+static int connection_pool = 0;
static set<string> source_paths;
static bool scan_files = false;
static map<string,string> scan_archives;
@@ -557,6 +560,16 @@ parse_opt (int key, char *arg,
concurrency = (unsigned) atoi(arg);
if (concurrency < 1) concurrency = 1;
break;
+ case 'C':
+ if (arg)
+ {
+ connection_pool = atoi(arg);
+ if (connection_pool < 2)
+ argp_failure(state, 1, EINVAL, "-C NUM minimum 2");
+ }
+ else // arg not given
+ connection_pool = std::thread::hardware_concurrency() * 2 ?: 2;
+ break;
case 'I':
// NB: no problem with unconditional free here - an earlier failed regcomp would exit program
if (passive_p)
@@ -3684,7 +3698,13 @@ sigusr2_handler (int /* sig */)
}
-
+static void // error logging callback from libmicrohttpd internals
+error_cb (void *arg, const char *fmt, va_list ap)
+{
+ (void) arg;
+ inc_metric("error_count","libmicrohttpd",fmt);
+ (void) vdprintf (STDERR_FILENO, fmt, ap);
+}
// A user-defined sqlite function, to score the sharedness of the
@@ -3829,7 +3849,7 @@ main (int argc, char *argv[])
// Start httpd server threads. Separate pool for IPv4 and IPv6, in
// case the host only has one protocol stack.
- MHD_Daemon *d4 = MHD_start_daemon (MHD_USE_THREAD_PER_CONNECTION
+ MHD_Daemon *d4 = MHD_start_daemon ((connection_pool ? 0 : MHD_USE_THREAD_PER_CONNECTION)
#if MHD_VERSION >= 0x00095300
| MHD_USE_INTERNAL_POLLING_THREAD
#else
@@ -3839,8 +3859,11 @@ main (int argc, char *argv[])
http_port,
NULL, NULL, /* default accept policy */
handler_cb, NULL, /* handler callback */
+ MHD_OPTION_EXTERNAL_LOGGER, error_cb, NULL,
+ (connection_pool ? MHD_OPTION_THREAD_POOL_SIZE : MHD_OPTION_END),
+ (connection_pool ? (int)connection_pool : MHD_OPTION_END),
MHD_OPTION_END);
- MHD_Daemon *d6 = MHD_start_daemon (MHD_USE_THREAD_PER_CONNECTION
+ MHD_Daemon *d6 = MHD_start_daemon ((connection_pool ? 0 : MHD_USE_THREAD_PER_CONNECTION)
#if MHD_VERSION >= 0x00095300
| MHD_USE_INTERNAL_POLLING_THREAD
#else
@@ -3851,6 +3874,9 @@ main (int argc, char *argv[])
http_port,
NULL, NULL, /* default accept policy */
handler_cb, NULL, /* handler callback */
+ MHD_OPTION_EXTERNAL_LOGGER, error_cb, NULL,
+ (connection_pool ? MHD_OPTION_THREAD_POOL_SIZE : MHD_OPTION_END),
+ (connection_pool ? (int)connection_pool : MHD_OPTION_END),
MHD_OPTION_END);
if (d4 == NULL && d6 == NULL) // neither ipv4 nor ipv6? boo
@@ -3904,6 +3930,8 @@ main (int argc, char *argv[])
if (! passive_p)
obatched(clog) << "search concurrency " << concurrency << endl;
+ obatched(clog) << "webapi connection pool " << connection_pool
+ << (connection_pool ? "" : " (unlimited)") << endl;
if (! passive_p)
obatched(clog) << "rescan time " << rescan_s << endl;
obatched(clog) << "fdcache fds " << fdcache_fds << endl;
@@ -1,3 +1,8 @@
+2021-12-08 Frank Ch. Eigler <fche@redhat.com>
+
+ PR28661
+ * debuginfod.8 (-C): Document new flag.
+
2021-11-05 Frank Ch. Eigler <fche@redhat.com>
PR28430
@@ -205,6 +205,23 @@ This important for controlling CPU-intensive operations like parsing
an ELF file and especially decompressing archives. The default is the
number of processors on the system; the minimum is 1.
+.TP
+.B "\-C" "\-C=NUM" "\-\-connection\-pool" "\-\-connection\-pool=NUM"
+Set the size of the pool of threads serving webapi queries. The
+following table summarizes the interpretaton of this option and its
+optional NUM parameter.
+.TS
+l l.
+no option clone new thread for every request, no fixed pool
+\-C use a fixed thread pool sized automatically
+\-C=NUM use a fixed thread pool sized NUM, minimum 2
+.TE
+
+The first mode is useful for friendly bursty traffic. The second mode
+is a simple and safe configuration based on the number of processors.
+The third mode is suitable for tuned load-limiting configurations
+facing unruly traffic.
+
.TP
.B "\-L"
Traverse symbolic links encountered during traversal of the PATHs,