The rationale here is that we should never need to try to send() at the
beginning of process_stream() because :
- if something was pending, it's very unlikely that it was unblocked
and not sent just between the last poll() and the wakeup instant.
- if something pending was recently sent, then we don't have anything
to send anymore.
So at first glance it doesn't seem like there could be any valid case
where trying to send before entering the function brings any benefit.
If a buffer allocation failed, we have SI_FL_WAIT_ROOM set and c_size(buf)
being zero. It's the only moment where we have a new opportunity to try to
allocate this buffer. However we don't want to waste our time trying this
if both are non-null since it indicates missing room without any changed
condition.
The vars_prune() and vars_init() functions involve locking while most of
the time there is no variable at all in streams nor sessions. Let's check
for emptiness before calling these functions. Simply doing this has
increased the multithreaded performance from 1.5 to 5% depending on the
workload.
The behaviour of the flag CF_WRITE_PARTIAL was modified by commit
95fad5ba4 ("BUG/MAJOR: stream-int: don't re-arm recv if send fails") due
to a situation where it could trigger an immediate wake up of the other
side, both acting in loops via the FD cache. This loss has caused the
need to introduce CF_WRITE_EVENT as commit c5a9d5bf, to replace it, but
both flags express more or less the same thing and this distinction
creates a lot of confusion and complexity in the code.
Since the FD cache now acts via tasklets, the issue worked around in the
first patch no longer exists, so it's more than time to kill this hack
and to restore CF_WRITE_PARTIAL's semantics (i.e.: there has been some
write activity since we last left process_stream).
This patch mostly reverts the two commits above. Only the part making
use of CF_WROTE_DATA instead of CF_WRITE_PARTIAL to detect the loss of
data upon connection setup was kept because it's more accurate and
better suited.
Make sure we call tasklet_free() only after si_release_endpoint(), when the
unsubscribe() method has been called, so that we're sure the mux won't
attempt to access the taslet.
Avoid using conn_xprt_want_send/recv, and totally nuke cs_want_send/recv,
from the upper layers. The polling is now directly handled by the connection
layer, it is activated on subscribe(), and unactivated once we got the event
and we woke the related task.
When retrying to connect to a server, because the previous connection failed,
make sure if we subscribed to the previous connection, the polling flags will
be true for the new fd.
No backport is needed.
In case pool_alloc() fails in stream_new(), we try to detach the stream
from the list before it has been added, dereferencing a NULL. In order
to fix it, simply move the LIST_DEL call upwards.
This must be backported to 1.8.
Make sure we unsubscribe from events before si_release_endpoint destroys
the conn_stream, or it will be never called. To do so, move the call to
unsubscribe to si_release_endpoint() directly.
This is 1.9-specific and shouldn't be backported.
When subscribing, we don't need to provide a list element, only the h2 mux
needs it. So instead, Add a list element to struct h2s, and use it when a
list is needed.
This forces us to use the unsubscribe method, since we can't just unsubscribe
by using LIST_DEL anymore.
This patch is larger than it should be because it includes some renaming.
These ones are mostly called from cfgparse.c for the parsing and do
not depend on the HTTP representation. The functions's prototypes
were moved to proto/http_rules.h, making this file work exactly like
tcp_rules. Ideally we should stop calling these functions directly
from cfgparse and register keywords, but there are a few cases where
that wouldn't work (stats http-request) so it's probably not worth
trying to go this far.
At the eand of process_stream(), we wake the task if there's something in
the input buffer, after attempting a recv. However this is wrong, and we should
only do so if we received new data. Just check the CF_READ_PARTIAL flag.
This is 1.9-specific and should not be backported.
Instead of using si_cs_io_cb() in process_stream() use si_cs_send/si_cs_recv
instead, as si_cs_io_cb() may lead to process_stream being woken up when it
shouldn't be, and thus timeout would never get triggered.
Instead of waiting for the connection layer to let us know we can read,
attempt to receive as soon as process_stream() is called, and subscribe
to receive events if we can't receive yet.
Now, except for idle connections, the recv(), send() and wake() methods are
no more, all the lower layers do is waking tasklet for anybody waiting
for I/O events.
The handshake processing time used to be stored per stream, which was
valid when there was exactly one stream per session. With H2 and
multiplexing it's not the case anymore and the reported handshake times
are wrong in the logs as it's computed between the TCP accept() and the
stream creation. Let's first move the handshake where it belongs, which
is the session.
However, this is not enough because we don't want to report an excessive
idle time either for H2 (since many requests use the connection).
So the solution used here is to have the stream retrieve sess->tv_accept
and the handshake duration when the stream is created, and let the mux
immediately reset them. This way, the handshake time becomes zero for the
second and subsequent requests in H2 (which was already the case in H1),
and the idle time exactly counts how long the connection remained unused
while it could be used, so in H1 it runs from the end of the previous
response and in H2 it runs from the end of the previous request since the
channel is already available.
This patch will need to be backported to 1.8.
The request counter is incremented when creating a new stream and when
resetting a stream, preparing for a new request. Unfortunately during
the thread migration this was missed, leading to non-atomic increments
in case threads are in use. The most visible side effect is that two
requests may have the same ID from time to time in the logs. However
the SPOE also uses this ID to route responses back to the stream so it
may also lead to occasional spurious SPOE timeouts.
Note that it still doesn't guarantee temporal unicity in the stream
identifiers since a long and a short connection could technically use
the same ID. The likeliness that this happens at the same time is almost
null (roughly threads*runqueue_depth/2^32 that it happens in the same
poll loop), but it will have to be addressed later anyway.
This patch must be backported to 1.8 with the other one it relies on
("MINOR: thread: implement HA_ATOMIC_XADD()").
When freeing the stream, make sure we remove the stream interfaces from the
wait lists, in case it was in there.
This is 1.9-specific, no backport is needed.
Instead of just using the conn_stream wait_list, give the stream_interface
its own. When the conn_stream will have its own buffers, the stream_interface
may have to wait on it.
This adds the set-priority-class and set-priority-offset actions to
http-request and tcp-request content. At this point they are not used
yet, which is the purpose of the next commit, but all the logic to
set and clear the values is there.
The current name is misleading as it implies a queue size, but the value
instead indicates a position in the queue.
The value is only the queue size at the exact moment the element is enqueued.
Soon we will gain the ability to insert anywhere into the queue, upon which
clarity of the name is more important.
We'll soon need to rely on the pendconn position at the time of dequeuing
to figure the position a stream took in the queue. Usually it's not a
problem since pendconn_free() is called once the connection starts, but
it will make a difference for failed dequeues (eg: queue timeout reached).
Thus it's important to call pendconn_free() before logging in cases we are
not certain whether it was already performed, and to call pendconn_unlink()
after we know the pendconn will not be used so that we collect the queue
state as accurately as possible. As a benefit it will also make the
server's and backend's queues count more accurate in these cases.
Now pendconn_free() takes a stream, checks that pend_pos is set, clears
it, and uses pendconn_unlink() to complete the job. It's cleaner and
centralizes all the bookkeeping work in pendconn_unlink() only and
ensures that there's a single place where the stream's position in the
queue is manipulated.
It remained some fragments of the old buffers API in debug messages, here and
there.
This was caused by the recent buffer API changes, no backport is needed.
Now all the code used to manipulate chunks uses a struct buffer instead.
The functions are still called "chunk*", and some of them will progressively
move to the generic buffer handling code as they are cleaned up.
Chunks are only a subset of a buffer (a non-wrapping version with no head
offset). Despite this we still carry a lot of duplicated code between
buffers and chunks. Replacing chunks with buffers would significantly
reduce the maintenance efforts. This first patch renames the chunk's
fields to match the name and types used by struct buffers, with the goal
of isolating the code changes from the declaration changes.
Most of the changes were made with spatch using this coccinelle script :
@rule_d1@
typedef chunk;
struct chunk chunk;
@@
- chunk.str
+ chunk.area
@rule_d2@
typedef chunk;
struct chunk chunk;
@@
- chunk.len
+ chunk.data
@rule_i1@
typedef chunk;
struct chunk *chunk;
@@
- chunk->str
+ chunk->area
@rule_i2@
typedef chunk;
struct chunk *chunk;
@@
- chunk->len
+ chunk->data
Some minor updates to 3 http functions had to be performed to take size_t
ints instead of ints in order to match the unsigned length here.
Now the buffers only contain the header and a pointer to the storage
area which can be anywhere. This will significantly simplify buffer
swapping and will make it possible to map chunks on buffers as well.
The buf_empty variable was removed, as now it's enough to have size==0
and area==NULL to designate the empty buffer (thus a non-allocated head
is the empty buffer by default). buf_wanted for now is indicated by
size==0 and area==(void *)1.
The channels and the checks now embed the buffer's head, and the only
pointer is to the storage area. This slightly increases the unallocated
buffer size (3 extra ints for the empty buffer) but considerably
simplifies dynamic buffer management. It will also later permit to
detach unused checks.
The way the struct buffer is arranged has proven quite efficient on a
number of tests, which makes sense given that size is always accessed
and often first, followed by the othe ones.
For the same consistency reasons, let's use b_empty() at the few places
where an empty buffer is expected, or c_empty() if it's done on a channel.
Some of these places were there to realign the buffer so
{b,c}_realign_if_empty() was used instead.
Passing unsigned ints everywhere is painful, and will cause some headache
later when we'll want to integrate better with struct ist which already
uses size_t. Let's switch buffers to use size_t instead.
Since applets are now part of the main scheduler, it's useful to report
their nice value and the number of calls to the applet handler, to see
where the CPU is spent.
There's no real reason to have a specific scheduler for applets anymore, so
nuke it and just use tasks. This comes with some benefits, the first one
being that applets cannot induce high latencies anymore since they share
nice values with other tasks. Later it will be possible to configure the
applets' nice value. The second benefit is that the applet scheduler was
not very thread-friendly, having a big lock around it in prevision of this
change. Thus applet-intensive workloads should now scale much better with
threads.
Some more improvement is possible now : some applets also use a task to
handle timers and timeouts. These ones could now be simplified to use only
one task.
In preparation for thread-specific runqueues, change the task API so that
the callback takes 3 arguments, the task itself, the context, and the state,
those were retrieved from the task before. This will allow these elements to
change atomically in the scheduler while the application uses the copied
value, and even to have NULL tasks later.
In order to use arbitrary data in the CLI (multiple lines or group of words
that must be considered as a whole, for example), it is now possible to add a
payload to the commands. To do so, the first line needs to end with a special
pattern: <<\n. Everything that follows will be left untouched by the CLI parser
and will be passed to the commands parsers.
Per-command support will need to be added to take advantage of this
feature.
Signed-off-by: Aurélien Nephtali <aurelien.nephtali@corp.ovh.com>
issue was identified by cppcheck
[src/map.c:372] -> [src/map.c:376]: (warning) Variable 'appctx->st2' is reassigned a value before the old one has been used. 'break;' missing?
[src/map.c:433] -> [src/map.c:437]: (warning) Variable 'appctx->st2' is reassigned a value before the old one has been used. 'break;' missing?
[src/map.c:555] -> [src/map.c:559]: (warning) Variable 'appctx->st2' is reassigned a value before the old one has been used. 'break;' missing?
[src/stream.c:3264] -> [src/stream.c:3268]: (warning) Variable 'appctx->st2' is reassigned a value before the old one has been used. 'break;' missing?
Signed-off-by: Ilya Shipitsin <chipitsine@gmail.com>
The management of the servers and the proxies queues was not thread-safe at
all. First, the accesses to <strm>->pend_pos were not protected. So it was
possible to release it on a thread (for instance because the stream is released)
and to use it in same time on another one (because we redispatch pending
connections for a server). Then, the accesses to stream's information (flags and
target) from anywhere is forbidden. To be safe, The stream's state must always
be updated in the context of process_stream.
So to fix these issues, the queue module has been refactored. A lock has been
added in the pendconn structure. And now, when we try to dequeue a pending
connection, we start by unlinking it from the server/proxy queue and we wake up
the stream. Then, it is the stream reponsibility to really dequeue it (or
release it). This way, we are sure that only the stream can create and release
its <pend_pos> field.
However, be careful. This new implementation should be thread-safe
(hopefully...). But it is not optimal and in some situations, it could be really
slower in multi-threaded mode than in single-threaded one. The problem is that,
when we try to dequeue pending connections, we process it from the older one to
the newer one independently to the thread's affinity. So we need to wait the
other threads' wakeup to really process them. If threads are blocked in the
poller, this will add a significant latency. This problem happens when maxconn
values are very low.
This patch must be backported in 1.8.
An fd cache entry might be removed and added at the end of the list, while
another thread is parsing it, if that happens, we may miss fd cache entries,
to avoid that, add a new field in the struct fdtab, "added_mask", which
contains a mask for potentially affected threads, if it is set, the
corresponding thread will set its bit in fd_cache_mask, to avoid waiting in
poll while it may have more work to do.
Create a local, per-thread, fdcache, for file descriptors that only belongs
to one thread, and make the global fd cache mostly lockless, as we can get
a lot of contention on the fd cache lock.
Since the fd update tables are per-thread, we need to have a bit per
thread to indicate whether an update exists, otherwise this can lead
to lost update events every time multiple threads want to update the
same FD. In practice *for now*, it only happens at start time when
listeners are enabled and ask for polling after facing their first
EAGAIN. But since the pollers are still shared, a lost event is still
recovered by a neighbor thread. This will not reliably work anymore
with per-thread pollers, where it has been observed a few times on
startup that a single-threaded listener would not always accept
incoming connections upon startup.
It's worth noting that during this code review it appeared that the
"new" flag in the fdtab isn't used anymore.
This fix should be backported to 1.8.
A number of counters have been added at special places helping better
understanding certain bug reports. These counters are maintained per
thread and are shown using "show activity" on the CLI. The "clear
counters" commands also reset these counters. The output is sent as a
single write(), which currently produces up to about 7 kB of data for
64 threads. If more counters are added, it may be necessary to write
into multiple buffers, or to reset the counters.
To backport to 1.8 to help collect more detailed bug reports.
James Mc Bride reported an interesting case affecting all versions since
at least 1.5 : if a client aborts a connection on an empty buffer at the
exact moment a server redispatch happens, the CF_SHUTW_NOW flag on the
channel is immediately turned into CF_SHUTW, which is not caught by
check_req_may_abort(), leading the redispatch to be performed anyway
with the channel marked as shut in both directions while the stream
interface correctly establishes. This situation makes no sense.
Ultimately the transfer times out and the server-side stream interface
remains in EST state while the client is in CLO state, and this case
doesn't correspond to anything we can handle in process_stream, leading
to poll() being woken up all the time without any progress being made.
And the session cannot even be killed from the CLI.
So we must ensure that check_req_may_abort() also considers the case
where the channel is already closed, which is what this patch does.
Thanks to James for providing detailed captures allowing to diagnose
the problem.
This fix must be backported to all maintained versions.
The H2 mux can cleanly report an error when a client closes, which is not
the case for the pass-through mux which only reports shutr. That was the
reason why "option abortonclose" was created since there was no way to
distinguish a clean shutdown after sending the request from an abort.
The problem is that in case of H2, the streams are always shut read after
the request is complete (when the END_STREAM flag is received), and that
when this lands on a backend configured with "option abortonclose", this
aborts the request. Disabling abortonclose is not always an option when
H1 and H2 have to coexist.
This patch makes use of the newly introduced mux capabilities reported
via the stream interface's SI_FL_CLEAN_ABRT indicating that the mux is
safe and that there is no need to turn a clean shutread into an abort.
This way abortonclose has no effect on requests initiated from an H2
mux.
This patch as well as these 3 previous ones need to be backported to
1.8 :
- BUG/MINOR: h2: properly report a stream error on RST_STREAM
- MINOR: mux: add flags to describe a mux's capabilities
- MINOR: stream-int: set flag SI_FL_CLEAN_ABRT when mux supports clean aborts
By copying the info in the stream interface that the mux cleanly reports
aborts, we'll have the ability to check this flag wherever needed regardless
of the presence of a mux or not.
Commit 3e13cba ("MEDIUM: session: make use of the connection's destroy
callback") ensured that connections could be autonomous to destroy the
session they initiated, but it didn't take care of doing the same for
applets. Such applets are used for peers, Lua and SPOE outgoing
connections. In this case, once the stream ends, it closes everything
and nothing takes care of releasing the session. The problem is not
immediately obvious since the only visible effect is that older
processes will not quit on reload after having leaked one such session.
For now we check in stream_free() if the session's origin is the applet
we're releasing, and then free the session as well. Something more
uniform should probably be done once we manage to unify applets and
connections a bit more.
This fix needs to be backported to 1.8. Thanks to Emmanuel Hocdet for
reporting the problem.
During the migration to the second version of the pools, the new
functions and pool pointers were all called "pool_something2()" and
"pool2_something". Now there's no more pool v1 code and it's a real
pain to still have to deal with this. Let's clean this up now by
removing the "2" everywhere, and by renaming the pool heads
"pool_head_something".
The cache exhibited a but in process_stream() where upon abort it is
possible to switch the stream-int's state to SI_ST_CLO without calling
si_release_endpoint(), resulting in a possibly missing ->release() for
the applet.
It should affect all other applets as well (eg: lua, spoe, peers) and
should carefully be backported to stable branches after some observation
period.
