global.h was one of the messiest files, it has accumulated tons of
implicit dependencies and declares many globals that make almost all
other file include it. It managed to silence a dependency loop between
server.h and proxy.h by being well placed to pre-define the required
structs, forcing struct proxy and struct server to be forward-declared
in a significant number of files.
It was split in to, one which is the global struct definition and the
few macros and flags, and the rest containing the functions prototypes.
The UNIX_MAX_PATH definition was moved to compat.h.
A few includes were missing in each file. A definition of
struct polled_mask was moved to fd-t.h. The MAX_POLLERS macro was
moved to defaults.h
Stdio used to be silently inherited from whatever path but it's needed
for list_pollers() which takes a FILE* and which can thus not be
forward-declared.
And also rename standard.c to tools.c. The original split between
tools.h and standard.h dates from version 1.3-dev and was mostly an
accident. This patch moves the files back to what they were expected
to be, and takes care of not changing anything else. However this
time tools.h was split between functions and types, because it contains
a small number of commonly used macros and structures (e.g. name_desc)
which in turn cause the massive list of includes of tools.h to conflict
with the callers.
They remain the ugliest files of the whole project and definitely need
to be cleaned and split apart. A few types are defined there only for
functions provided there, and some parts are even OS-specific and should
move somewhere else, such as the symbol resolution code.
This splits the hathreads.h file into types+macros and functions. Given
that most users of this file used to include it only to get the definition
of THREAD_LOCAL and MAXTHREADS, the bare minimum was placed into thread-t.h
(i.e. types and macros).
All the thread management was left to haproxy/thread.h. It's worth noting
the drop of the trailing "s" in the name, to remove the permanent confusion
that arises between this one and the system implementation (no "s") and the
makefile's option (no "s").
For consistency, src/hathreads.c was also renamed thread.c.
A number of files were updated to only include thread-t which is the one
they really needed.
Some future improvements are possible like replacing empty inlined
functions with macros for the thread-less case, as building at -O0 disables
inlining and causes these ones to be emitted. But this really is cosmetic.
File buf.h is one common cause of pain in the dependencies. Many files in
the code need it to get the struct buffer definition, and a few also need
the inlined functions to manipulate a buffer, but the file used to depend
on a long chain only for BUG_ON() (addressed by last commit).
Now buf.h is split into buf-t.h which only contains the type definitions,
and buf.h for all inlined functions. Callers who don't care can continue
to use buf.h but files in types/ must only use buf-t.h. sys/types.h had
to be added to buf.h to get ssize_t as used by b_move(). It's worth noting
that ssize_t is only supposed to be a size_t supporting -1, so b_move()
ought to be rethought regarding this.
The files were moved to haproxy/ and all their users were updated
accordingly. A dependency issue was addressed on fcgi whose C file didn't
include buf.h.
Fortunately that file wasn't made dependent upon haproxy since it was
integrated, better isolate it before it's too late. Its dependency on
api.h was the result of the change from config.h, which in turn wasn't
correct. It was changed back to stddef.h for size_t and sys/types.h for
ssize_t. The recently added reference to MAX() was changed as it was
placed only to avoid a zero length in the non-free-standing version and
was causing a build warning in the hpack encoder.
All files that were including one of the following include files have
been updated to only include haproxy/api.h or haproxy/api-t.h once instead:
- common/config.h
- common/compat.h
- common/compiler.h
- common/defaults.h
- common/initcall.h
- common/tools.h
The choice is simple: if the file only requires type definitions, it includes
api-t.h, otherwise it includes the full api.h.
In addition, in these files, explicit includes for inttypes.h and limits.h
were dropped since these are now covered by api.h and api-t.h.
No other change was performed, given that this patch is large and
affects 201 files. At least one (tools.h) was already freestanding and
didn't get the new one added.
I changed my mind twice on this one and pushed after the last test with
threads disabled, without re-enabling long long, causing this rightful
build warning.
This needs to be backported if the previous commit ff64d3b027 ("MINOR:
threads: export the POSIX thread ID in panic dumps") is backported as
well.
It is very difficult to map a panic dump against a gdb thread dump
because the thread numbers do not match. However gdb provides the
pthread ID but this one is supposed to be opaque and not to be cast
to a scalar.
This patch provides a fnuction, ha_get_pthread_id() which retrieves
the pthread ID of the indicated thread and casts it to an unsigned
long long so as to lose the least possible amount of information from
it. This is done cleanly using a union to maintain alignment so as
long as these IDs are stored on 1..8 bytes they will be properly
reported. This ID is now presented in the panic dumps so it now
becomes possible to map these threads. When threads are disabled,
zero is returned. For example, this is a panic dump:
Thread 1 is about to kill the process.
*>Thread 1 : id=0x7fe92b825180 act=0 glob=0 wq=1 rq=0 tl=0 tlsz=0 rqsz=0
stuck=1 prof=0 harmless=0 wantrdv=0
cpu_ns: poll=5119122 now=2009446995 diff=2004327873
curr_task=0xc99bf0 (task) calls=4 last=0
fct=0x592440(task_run_applet) ctx=0xca9c50(<CLI>)
strm=0xc996a0 src=unix fe=GLOBAL be=GLOBAL dst=<CLI>
rqf=848202 rqa=0 rpf=80048202 rpa=0 sif=EST,200008 sib=EST,204018
af=(nil),0 csf=0xc9ba40,8200
ab=0xca9c50,4 csb=(nil),0
cof=0xbf0e50,1300:PASS(0xc9cee0)/RAW((nil))/unix_stream(20)
cob=(nil),0:NONE((nil))/NONE((nil))/NONE(0)
call trace(20):
| 0x59e4cf [48 83 c4 10 5b 5d 41 5c]: wdt_handler+0xff/0x10c
| 0x7fe92c170690 [48 c7 c0 0f 00 00 00 0f]: libpthread:+0x13690
| 0x7ffce29519d9 [48 c1 e2 20 48 09 d0 48]: linux-vdso:+0x9d9
| 0x7ffce2951d54 [eb d9 f3 90 e9 1c ff ff]: linux-vdso:__vdso_gettimeofday+0x104/0x133
| 0x57b484 [48 89 e6 48 8d 7c 24 10]: main+0x157114
| 0x50ee6a [85 c0 75 76 48 8b 55 38]: main+0xeaafa
| 0x50f69c [48 63 54 24 20 85 c0 0f]: main+0xeb32c
| 0x59252c [48 c7 c6 d8 ff ff ff 44]: task_run_applet+0xec/0x88c
Thread 2 : id=0x7fe92b6e6700 act=0 glob=0 wq=0 rq=0 tl=0 tlsz=0 rqsz=0
stuck=0 prof=0 harmless=1 wantrdv=0
cpu_ns: poll=786738 now=1086955 diff=300217
curr_task=0
Thread 3 : id=0x7fe92aee5700 act=0 glob=0 wq=0 rq=0 tl=0 tlsz=0 rqsz=0
stuck=0 prof=0 harmless=1 wantrdv=0
cpu_ns: poll=828056 now=1129738 diff=301682
curr_task=0
Thread 4 : id=0x7fe92a6e4700 act=0 glob=0 wq=0 rq=0 tl=0 tlsz=0 rqsz=0
stuck=0 prof=0 harmless=1 wantrdv=0
cpu_ns: poll=818900 now=1153551 diff=334651
curr_task=0
And this is the gdb output:
(gdb) info thr
Id Target Id Frame
* 1 Thread 0x7fe92b825180 (LWP 15234) 0x00007fe92ba81d6b in raise () from /lib64/libc.so.6
2 Thread 0x7fe92b6e6700 (LWP 15235) 0x00007fe92bb56a56 in epoll_wait () from /lib64/libc.so.6
3 Thread 0x7fe92a6e4700 (LWP 15237) 0x00007fe92bb56a56 in epoll_wait () from /lib64/libc.so.6
4 Thread 0x7fe92aee5700 (LWP 15236) 0x00007fe92bb56a56 in epoll_wait () from /lib64/libc.so.6
We can clearly see that while threads 1 and 2 are the same, gdb's
threads 3 and 4 respectively are haproxy's threads 4 and 3.
This may be backported to 2.0 as it removes some confusion in github issues.
Move the definition of WDTSIG and DEBUGSIG from wdt.c and debug.c into
types/signal.h, so that we can access them in another file.
We need those definition to avoid blocking those signals when running
__signal_process_queue().
This should be backported to 2.1, 2.0 and 1.9.
It's more generic and versatile than the previous shut_your_big_mouth_gcc()
that was used to silence annoying warnings as it's not limited to ignoring
syscalls returns only. This allows us to get rid of the aforementioned
function and the shut_your_big_mouth_gcc_int variable, that started to
look ugly in multi-threaded environments.
This command is used to produce an arbitrary amount of data on the
output. It can be used to test the CLI's state machine as well as
the internal parts related to applets an I/O. A typical test consists
in asking for all sizes from 0 to 16384:
$ (echo "prompt;expert-mode on";for i in {0..16384}; do
echo "debug dev write $i"; done) | socat - /tmp/sock1 | wc -c
134258738
A better test would consist in first waiting for the response before
sending a new request.
This command is not restricted to the admin since it's harmless.
Instead of special-casing the use of the symbol resolving to decide
whether to dump a partial or complete trace, let's simply start over
and dump everything when we reach the end after having found nothing.
It will be more robust against dirty traces as well.
It happens that on aarch64 backtrace() only returns one entry (tested
with gcc 4.7.4, 5.5.0 and 7.4.1). Probably that it refrains from unwinding
the stack due to the risk of hitting a bad pointer. Here we can use
may_access() to know when it's safe, so we can actually unwind the stack
without taking risks. It happens that the faulting function (the one
just after the signal handler) is not listed here, very likely because
the signal handler uses a special stack and did not create a new frame.
So this patch creates a new my_backtrace() function in standard.h that
either calls backtrace() or does its own unrolling. The choice depends
on HA_HAVE_WORKING_BACKTRACE which is set in compat.h based on the build
target.
It's useful to get an indication of unresolved stuff or memory
corruption to have the apparent depth of the stack trace in the
output, especially if we dump nothing.
Calling backtrace() will access libgcc at runtime. We don't want to do
it after the chroot, so let's perform a first call to have it ready in
memory for later use.
When a panic() occurs due to a stuck thread, we'll try to dump a
backtrace of this thread if the config directive USE_BACKTRACE is
set (which is the case on linux+glibc). For this we use the
backtrace() call provided by glibc and iterate the pointers through
resolve_sym_name(). In order to minimize the output (which is limited
to one buffer), we only do this for stuck threads, and we start the
dump above ha_panic()/ha_thread_dump_all_to_trash(), and stop when
meeting known points such as main/run_tasks_from_list/run_poll_loop.
If enabled without USE_DL, the dump will be complete with no details
except that pointers will all be given relative to main, which is
still better than nothing.
The new USE_BACKTRACE config option is enabled by default on glibc since
it has been present for ages. When it is set, the export-dynamic linker
option is enabled so that all non-static symbols are properly resolved.
Now in "show threads", the task/tasklet handler will be resolved
using this function, which will provide more detailed results and
will still support offsets to main for unresolved symbols.
It happens that just sending the debug signal to the process makes on
thread wait for its turn while nobody wants to dump. We need to at
least verify that a dump was really requested for this thread.
This can be backported to 2.1 and 2.0.
Often in crash dumps we see unknown function pointers. Let's display
them relative to main, that helps quite a lot figure the function
from an executable, for example:
(gdb) x/a main+645360
0x4c56a0 <h1_timeout_task>: 0x2e6666666666feeb
This could be backported to 2.0.
We used to mix high latency tasks and low latency tasklets in the same
list, and to even refill bulk tasklets there, causing some unfairness
in certain situations (e.g. poll-less transfers between many connections
saturating the machine with similarly-sized in and out network interfaces).
This patch changes the mechanism to split the load into 3 lists depending
on the task/tasklet's desired classes :
- URGENT: this is mainly for tasklets used as deferred callbacks
- NORMAL: this is for regular tasks
- BULK: this is for bulk tasks/tasklets
Arbitrary ratios of max_processed are picked from each of these lists in
turn, with the ability to complete in one list from what was not picked
in the previous one. After some quick tests, the following setup gave
apparently good results both for raw TCP with splicing and for H2-to-H1
request rate:
- 0 to 75% for urgent
- 12 to 50% for normal
- 12 to what remains for bulk
Bulk is not used yet.
popen() is annoying because it doesn't catch stderr. The command was
implemented using it just by pure laziness, let's just redo it a bit
cleaner using normal syscalls. Note that this command is only enabled
when built with -DDEBUG_DEV.
As reported in issue #343, there is one case where a NULL stream can
still be dereferenced, when getting &s->txn->flags. Let's protect all
assignments to stay on the safe side for future additions.
No backport is needed.
Debug commands will usually mark the fate of the process. We'd rather
have them counted and visible in a core or in stats output than trying
to guess how a flag combination could happen. The counter is only
incremented when the command is about to be issued however, so that
failed attempts are ignored.
Instead of relying on DEBUG_DEV for most debugging commands, which is
limiting, let's condition them to expert mode. Only one ("debug dev exec")
remains conditionned to DEBUG_DEV because it can have a security implication
on the system. The commands are not listed unless "expert-mode on" was first
entered on the CLI :
> expert-mode on
> help
debug dev close <fd> : close this file descriptor
debug dev delay [ms] : sleep this long
debug dev exec [cmd] ... : show this command's output
debug dev exit [code] : immediately exit the process
debug dev hex <addr> [len]: dump a memory area
debug dev log [msg] ... : send this msg to global logs
debug dev loop [ms] : loop this long
debug dev panic : immediately trigger a panic
debug dev stream ... : show/manipulate stream flags
debug dev tkill [thr] [sig] : send signal to thread
> debug dev stream
Usage: debug dev stream { <obj> <op> <value> | wake }*
<obj> = {strm | strm.f | sif.f | sif.s | sif.x | sib.f | sib.s | sib.x |
txn.f | req.f | req.r | req.w | res.f | res.r | res.w}
<op> = {'' (show) | '=' (assign) | '^' (xor) | '+' (or) | '-' (andnot)}
<value> = 'now' | 64-bit dec/hex integer (0x prefix supported)
'wake' wakes the stream asssigned to 'strm' (default: current)
This function adds some control by verifying that the target address is
really readable. It will not protect against writing to wrong places,
but will at least protect against a large number of mistakes such as
incorrectly copy-pasted addresses.
This new "debug dev stream" command allows to manipulate flags, timeouts,
states for streams, channels and stream interfaces, as well as waking a
stream up. These may be used to help reproduce certain bugs during
development. The operations are performed to the stream assigned by
"strm" which defaults to the CLI's stream. This stream pointer can be
chosen from one of those reported in "show sess". Example:
socat - /tmp/sock1 <<< "debug dev stream strm=0x1555b80 req.f=-1 req.r=now wake"
As using an mt_list for the tasklet list is costly, instead use a regular list,
but add an mt_list for tasklet woken up by other threads, to be run on the
current thread. At the beginning of process_runnable_tasks(), we just take
the new list, and merge it into the task_list.
This should give us performances comparable to before we started using a
mt_list, but allow us to use tasklet_wakeup() from other threads.
The aim is to rassemble all scheduler information related to the current
thread. It simply points to task_per_thread[tid] without having to perform
the operation at each time. We save around 1.2 kB of code on performance
sensitive paths and increase the request rate by almost 1%.
Change the tasklet code so that the tasklet list is now a mt_list.
That means that tasklet now do have an associated tid, for the thread it
is expected to run on, and any thread can now call tasklet_wakeup() for
that tasklet.
One can change the associated tid with tasklet_set_tid().
When we dump a thread's state (show thread, panic) we don't know if
anything is happening in Lua, which can be problematic especially when
calling external functions. With this patch, the thread dump code can
now detect if we're running in a global Lua task (hlua_process_task),
or in a TCP or HTTP Lua service (task_run_applet and applet.fct ==
hlua_applet_tcp_fct or http_applet_http_fct), or a fetch/converter
from an analyser (s->hlua != NULL). In such situations, it's able to
append a formatted Lua backtrace of the Lua execution path with
function names, file names and line numbers.
Note that a shorter alternative could be to call "luaL_where(hlua->T,0)"
which only prints the current location, but it's not necessarily sufficient
for complex code.
There were 221 places where a status message or an error message were built
to be returned on the CLI. All of them were replaced to use cli_err(),
cli_msg(), cli_dynerr() or cli_dynmsg() depending on what was expected.
This removed a lot of duplicated code because most of the times, 4 lines
are replaced by a single, safer one.
It happens that upon looping threads the watchdog fires, starts a dump,
and other threads expire their budget while waiting for the other threads
to get dumped and trigger a watchdog event again, adding some confusion
to the traces. With this patch the situation becomes clearer as we export
the list of threads being dumped so that the watchdog can check it before
deciding to trigger. This way such threads in queue for being dumped are
not attempted to be reported in turn.
This should be backported to 2.0 as it helps understand stack traces.
If a thread dump is requested from a signal handler, it may interrupt
a thread already waiting for a dump to complete, and may see the
threads_to_dump variable go to zero while others are waiting, steal
the lock and prevent other threads from ever completing. This tends
to happen when dumping many threads upon a watchdog timeout, to threads
waiting for their turn.
Instead now we proceed in two steps :
1) the last dumped thread sets all bits again
2) all threads only wait for their own bit to appear, then clear it
and quit
This way there's no risk that a bit performs a double flip in the same
loop and threads cannot get stuck here anymore.
This should be backported to 2.0 as it clarifies stack traces.
Now that the architecture was changed so that attempts to receive/send data
always come from the upper layers, instead of them only trying to do so when
the lower layer let them know they could try, we can finally get rid of the
fd cache. We don't really need it anymore, and removing it gives us a small
performance boost.
gcc (Ubuntu 5.4.0-6ubuntu1~16.04.11) 5.4.0 20160609
Copyright (C) 2015 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
complains:
> src/debug.c: In function "ha_panic":
> src/debug.c:162:2: warning: ignoring return value of "write", declared with attribute warn_unused_result [-Wunused-result]
> (void) write(2, trash.area, trash.data);
> ^
Remove the active_tasks_mask variable, we can deduce if we've work to do
by other means, and it is costly to maintain. Instead, introduce a new
function, thread_has_tasks(), that returns non-zero if there's tasks
scheduled for the thread, zero otherwise.
This flag is constantly cleared by the scheduler and will be set by the
watchdog timer to detect stuck threads. It is also set by the "show
threads" command so that it is easy to spot if the situation has evolved
between two subsequent calls : if the first "show threads" shows no stuck
thread and the second one shows such a stuck thread, it indicates that
this thread didn't manage to make any forward progress since the previous
call, which is extremely suspicious.
Whenever we can retrieve a valid stream pointer, we now call stream_dump()
to get a detailed dump of the stream currently running on the processor.
This is used by "show threads" and by ha_panic().
The current choice of SIGPWR has the adverse effect of stopping gdb each
time it is triggered using "show threads" or example, which is not really
convenient. Let's switch to SIGURG instead, which we don't use either.
Now we can report each thread's CPU time, both at wake up (poll) and
retrieved while dumping (now), then the difference, which directly
indicates how long the thread has been running uninterrupted. A very
high value for the diff could indicate a deadlock, especially if it
happens between two threads. Note that it may occasionally happen
that a wrong value is displayed since nothing guarantees that the
date is read atomically.
It's a bit too easy to crash by accident when using dump_hex() on any
area. Let's have a function to check if the memory may safely be read
first. This one abuses the stat() syscall checking if it returns EFAULT
or not, in which case it means we're not allowed to read from there. In
other situations it may return other codes or even a success if the
area pointed to by the file exists. It's important not to abuse it
though and as such it's tested only once per output line.
When haproxy is built with DEBUG_DEV, the following commands are added
to the CLI :
debug dev close <fd> : close this file descriptor
debug dev delay [ms] : sleep this long
debug dev exec [cmd] ... : show this command's output
debug dev exit [code] : immediately exit the process
debug dev hex <addr> [len]: dump a memory area
debug dev log [msg] ... : send this msg to global logs
debug dev loop [ms] : loop this long
debug dev panic : immediately trigger a panic
debug dev tkill [thr] [sig] : send signal to thread
These are essentially aimed at helping developers trigger certain
conditions and are expected to be complemented over time.
This function dumps all existing threads using the thread dump mechanism
then aborts. This will be used by the lockup detection and by debugging
tools.
This way we'll be able to store more per-thread information than just
the pthread pointer. The storage became an array of struct instead of
an allocated array since it's very small (typically 512 bytes) and not
worth the hassle of dealing with memory allocation on this. The array
was also renamed thread_info to make its intended usage more explicit.
The current "show threads" command was too limited as it was not possible
to dump other threads' detailed states (e.g. their tasks). This patch
goes further by using thread signals so that each thread can dump its
own state in turn into a shared buffer provided by the caller. Threads
are synchronized using a mechanism very similar to the rendez-vous point
and using this method, each thread can safely dump any of its contents
and the caller can finally report the aggregated ones from the buffer.
It is important to keep in mind that the list of signal-safe functions
is limited, so we take care of only using chunk_printf() to write to a
pre-allocated buffer.
This mechanism is enabled by USE_THREAD_DUMP and is enabled by default
on Linux 2.6.28+. On other platforms it falls back to the previous
solution using the loop and the less precise dump.
tasklets don't have a call date, so when a tasklet is cast into a task
and is present at the end of a page we run a risk of dereferencing
unmapped memory when dumping them in ha_task_dump(). This commit
simplifies the test and uses to distinct calls for tasklets and tasks.
No backport is needed.
Instead of having them dump into the trash and initialize it, let's have
the caller initialize a buffer and pass it. This will be convenient to
dump multiple threads at once into a single buffer.
The new function ha_thread_dump() will dump debugging info about all known
threads. The current thread will contain a bit more info. The long-term goal
is to make it possible to use it in signal handlers to improve the accuracy
of some dumps.
The function dumps its output into the trash so as it was trivial to add,
a new "show threads" command appeared on the CLI.
