Introduce a mechanism to suppress exceptions which do not produce a
full stack trace for common known cases where a loop should be aborted.
Use this mechanism to suppress the infamous "FIXME" exception.
Reduce the log level to at most NOTICE, and in some cases DEBUG.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
Capture SIGINT and SIGTERM and shut down, preserving current completed
crawl and hash table state.
* Executing tasks are completed, queued tasks are paused.
* Crawl state is saved.
* The crawl master and crawl writeback threads are terminated.
* The task queue is flushed.
* Dirty hash table extents are flushed.
* Hash prefetch and writeback threads are terminated.
* Hash table is deallocated.
* FD caches and tmpfiles are destroyed.
* Assuming the above didn't crash or deadlock, bees exits.
The above order isn't the fastest, but it does roughly follow the
shared_ptr dependencies and avoids data races--especially those that
might lead to bees reporting an extent scanned when it was only queued
for future scanning that did not occur.
In case of a violation of expected shared_ptr dependency order,
exceptions in BeesContext child object accessor methods (i.e. roots(),
hash_table(), etc) prevent any further progress in threads that somehow
remain unexpectedly active.
Move some threads from main into BeesContext so they can be stopped
via BeesContext. The main thread now runs a loop waiting for signals.
A slow FD leak was discovered in TempFile handling. This has not been
fixed yet, but an implementation detail of the C++ runtime library makes
the leak so slow it may never be important enough to fix.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
The deadlock seems to be fixed now (if there ever was one--there certainly
were deadlocks, but matching deadlocks to root causes is non-trivial
and a number of distinct deadlock cases have been fixed in recent years).
The benchmark data is inconclusive about whether it is better to fsync or
not to fsync. A paranoia option might be useful here.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
After weeks of testing I copied part of a change to main without copying
the rest of the change, leading to an immediate segfault on startup.
So here is the rest of the change: limit the number of
BeesContexts per process to 1. This change was discussed at
https://github.com/Zygo/bees/issues/54#issuecomment-360332529 but there
are more reasons to do it now: the candidates to replace the current
hash table format are less forgiving of sharing hash tables, and it may
even become necessary to have more than one hash table per BeesContext
instance (e.g. to keep datasum and nodatasum data separate).
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
https://github.com/Zygo/bees/issues/91 describes problems encountered
when running bees on systems with many CPU cores.
Limit the computed number of threads (using --thread-factor or the
default) to a maximum of 8 (i.e. the number of logical cores in a modern
laptop). Users can override the limit by using --thread-count.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
Introduce --workaround options which trade performance or effectiveness to
avoid triggering kernel bugs.
The first such option is --workaround-btrfs-send, which avoids making any
modification to read-only subvols to avoid btrfs send bugs.
Clean up usage message: no tabs for formatting, split options into
sections by theme.
Make scan mode a non-static data member like all (most?) other options.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
The -g option limits the number of worker threads when the target load
average is exceeded. On some systems the load normally runs high, and
continuous bees operation is required to avoid running out of disk space.
Add a -G/--thread-min option to force at least some threads to continue
running.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
Add -g / --loadavg-target parameter to track system load and add or
remove bees worker threads dynamically to keep system load close to the
loadavg target. Thread count may vary from zero to the maximum
specified by -c or -C, and is adjusted every 5 seconds.
This is better than implementing a similar load average scheme from
outside of the process (though that is still possible) because the
in-process load tracker does not disrupt the performance timing feedback
mechanisms as a freezer cgroup or SIGSTOP would when controlling bees
from outside. The internal load average tracker can also adjust the
number of active threads while an external tracker can only choose from
the maximum or zero.
Also fix a bug where a Task could deadlock waiting for itself to exit
if it tries to insert a new Task after the number of worker threads has
been set to zero.
Also correct usage message for --scan-mode (values are 0..2) since
we are touching adjacent lines anyway.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
Log messages were already labelled with log levels, but there was no
way to filter by log level at run time.
Implement the filter inside the bees process so it can skip evaluation
of the BEESLOG* arguments if the log messages would not be emitted.
Fixes: https://github.com/Zygo/bees/issues/67
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
Having too many "write a message to the log" primitives is confusing,
and having one that intermittently and silently discards output is even
_more_ confusing.
Replace all BEESINFO with appropriate BEESLOG*s. Usually DEBUG.
Except for one or two that occur too often. Just delete those.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
Since we are now unconditionally rendering the print_fn as a static
string, there is no need for it to be a function. We also need it to
be brief and mostly constant.
Use a string instead. Put the string before the function in the Task
constructor arguments so that the title string appears as a heading in
code, since we are making a breaking API change already.
Drop TASK_MACRO as it is broken by this change, but there is no similar
usage of Task anywhere to make it worth fixing.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
Move pthread_setname_np to the same place we do pthread_getname_np.
Detect errors in pthread_getname_np--but don't throw an exception
because we would call ourself recursively from the exception handler
when it tries to log the exception.
Fix the order of set_name and the first BEESNOTE/BEESLOG call in threads,
closing small time intervals where logs have the wrong thread name,
and that wrong name becomes persistent for the thread.
Make the main thread's name "bees" because Linux kernel stack traces use
the pthread name of the main thread instead of the name of the process.
Anonymous threads get the process name (usually "bees"). We should not
have any such threads, but we do. This appears to occur mostly during
exception stack unwinding. GCC/pthread bug?
Fixes: https://github.com/Zygo/bees/issues/51
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
When a Task worker thread is executing a Task, the thread name is less
useful than the Task description.
Use the Task description instead of the thread name if the thread has
no BeesThread name and the thread is currently executing a task.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
Threads from the Task module in libcrucible don't set BeesNote::tl_name.
Even if they did, in Task context the thread name is unspecific to the point
of meaninglessness.
Use the Task::print method as the name for such threads, and be sure
that future Task print functions are designed for that usage.
The extra complexity in BeesNote::get_name() seems preferable to
bombarding pthread_setname_np hundreds or thousands of times per second.
FIXME: we are now calling Task::print() on every BeesNote, which
is effectively unconditionally. Maybe we should have Task::print()
and get_name() return a closure, or just evaluate Task::print() once
and cache it in TaskState, or define Task's constructor with a string
argument instead of the current print_fn closure.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
This commit adds log levels to the output. In systemd, it makes colored
lines, otherwise it's probably just a number. Bees is very chatty, so
this paves the road for log level filtering.
Signed-off-by: Kai Krakow <kai@kaishome.de>
There are two subvol scan algorithms implemented so far. The two modes
are unimaginatively named 0 and 1.
0: sorts extents by (inode, subvol, offset),
1: scans extents round-robin from all subvols.
Algorithm 0 scans references to the same extent at close to the same
time, which is good for performance; however, whenever a snapshot is
created, the scan of the entire filesystem restarts at the beginning of
the new snapshot.
Algorithm 1 makes continuous forward progress even when new snapshots
are created, but it does not benefit from caching and will force the
kernel to reread data multiple times when there are snapshots.
The algorithm can be selected at run-time using the -m or --scan-mode
option.
We can collect some field data on these before replacing them with
an extent-tree-based scanner. Alternatively, for pre-4.14 kernels,
we can keep these two modes as non-default options.
Currently these algorithms have terrible names. TODO: fix that, but
also TODO: delete all that code and do scans directly from the extent
tree instead.
Augment the scan algorithms relative to their earlier implementation by
batching multiple extents to scan from each subvol before switching to
a different subvol.
Sprinkle some BEESNOTEs on the Task objects so that they don't
disappear from the thread status output.
Adjust some timing constants to deal with the increased latency from
competing threads.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
Distribute incoming extents across a thread pool for faster execution
on multi-core, multi-disk environments.
Switch extent enumeration model to scan extent refs consecutively(ish).
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
Remove some dead code because dedup-related deadlocks have not been
observed since Linux kernel v4.11.
Preserve rationale of remaining #if 0 block (why we do write/rename
instead of write/fsync/rename) so that people don't try to replace the
"missing" fsync() there.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
With kernel 4.14 there is no sign of the previous LOGICAL_INO performance
problems, so there seems to be no need to throttle threads using this
ioctl.
Increase the FD cache size limits and scan thread count. Let the kernel
figure out scheduling.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
GCC 7 and higher turn a previous warning into an error for implicit
fallthrough. Let's hint the compiler that this is intentional here.
Signed-off-by: Kai Krakow <kai@kaishome.de>
Adjust bees to match changes in Chatter's interface.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
(cherry picked from commit 66fd28830d42acbd837dfb08b89a1f9c05c6d474)
To make bees more friendly to use with syslog/systemd, we add an option
to omit timestamps from the log output.
Signed-off-by: Kai Krakow <kai@kaishome.de>
This commit adds a simple getopt options parser to show help. This can
be used as a boilerplate for adding more options later.
Signed-off-by: Kai Krakow <kai@kaishome.de>
Add time spent in file create and copy operations to the stats.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
(cherry picked from commit f01c20f97269083175a74d1a1fd3ebaced2d9560)
A BEESTRACE closure could throw an exception. Trap those so we don't
end up in terminate().
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
(cherry picked from commit 59660cfc00b9ca233eeb1a7cdf6df34a45a2deba)
Some whitespace fixes. Remove some duplicate code. Don't lock
two BeesStats objects in the - operator method.
Get the locking for T& at(const K&) right to avoid locking a mutex
recursively. Make the non-const version of the function private.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
"s_name" was a thread_local variable, not static, and did not require a
mutex to protect access. A deadlock is possible if a thread triggers an
exception with a handler that attempts to log a message (as the top-level
exception handler in bees does).
Remove multiple unnecessary mutex locks. Rename the thread_local variables
to make their scope clearer.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
This fixes a bug where bees tries to process itself as a btrfs filesystem.
This is a species of bug that I only notice *after* pushing to a public
git repo.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
Every git commit was causing bees.cc and bees-hash.cc to be rebuilt,
which was expensive and unnecessary.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
btrfs provides a flush on rename when the rename target exists, so the
fsync is not necessary. In the initialization case (when the rename
target does not exist and the implicit flush does not occur), the file
may be empty or a hole after a crash. Bees treats this case the same
as if the file did not exist. Since this condition occurs for only the
first 15 minutes of the lifetime of a bees installation, it's not worth
bothering to fix.
If we attempt to fsync the file ourselves, on a crash with log replay,
btrfs will end up with a directory entry pointing to a non-existent inode.
This directory entry cannot be deleted or renamed except by deleting
the entire subvol. On large filesystems this bug is triggered by nearly
every crash (verified on kernels up to 4.5.7).
Remove the fsync to avoid the btrfs bug, and accept the failure mode
that occurs in the first 15 minutes after a bees install.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
