In that level no io_priority_class-es exist. Instead, all the IO happens
in the context of current sched-group. File API no longer accepts prio
class argument (and makes io_intent arg mandatory to impls).
So the change consists of
- removing all usage of io_priority_class
- patching file_impl's inheritants to updated API
- priority manager goes away altogether
- IO bandwidth update is performed on respective sched group
- tune-up scylla-gdb.py io_queues command
The first change is huge and was made semi-autimatically by:
- grep io_priority_class | default_priority_class
- remove all calls, found methods' args and class' fields
Patching file_impl-s is smaller, but also mechanical:
- replace io_priority_class& argument with io_intent* one
- pass intent to lower file (if applicatble)
Dropping the priority manager is:
- git-rm .cc and .hh
- sed out all the #include-s
- fix configure.py and cmakefile
The scylla-gdb.py update is a bit hairry -- it needs to use task queues
list for IO classes names and shares, but to detect it should it checks
for the "commitlog" group is present.
Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>
Closes#13963
The command prints segment_manager address, because it's the manager
who's on interest, not the db::commitlog itself. Also it prints out all
found segments, it's just for convenience -- segments are in a vector of
shared pointers and it's handy to have object addresses instantly.
Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>
Closes#14088
All users of global proxy are gone (*), proxy can be made fully main/cql_test_env local.
(*) one test case still needs it, but can get it via cql_test_env
Closes#13616
* github.com:scylladb/scylladb:
code: Remove global proxy
schema_change_test: Use proxy from cql_test_env
test: Carry proxy reference on cql_test_env
Adjust scylla-gdb.get_gms_version_value
to get the versioned_value version as version_type
(utils::tagged_integer).
Signed-off-by: Benny Halevy <bhalevy@scylladb.com>
Prepare for next patch that makes gms::versioned_value
members private, and provides methods by the same name
as the current members.
Signed-off-by: Benny Halevy <bhalevy@scylladb.com>
No code needs global proxy anymore. Keep on-stack values in main and
cql_test_env and keep the pointer on debug:: namespace.
Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>
To avoid confusion with task manager tasks compaction::task is renamed
to compaction::compaction_task_exector. All inheriting classes are
modified similarly.
compaction_manager::task needs to be accessed from task manager compaction
tasks. Thus, compaction_manager::task and all inheriting classes are moved
from compaction manager to compaction namespace.
A read that requested memory and has to wait for it can be registered as inactive. This can happen for example if the memory request originated from a background I/O operation (a read-ahead maybe).
Handling this case is currently very difficult. What we want to do is evict such a read on-the-spot: the fact that there is a read waiting on memory means memory is in demand and so inactive reads should be evicted. To evict this reader, we'd first have to remove it from the memory wait list, which is almost impossible currently, because `expiring_fifo<>`, the type used for the wait list, doesn't allow for that. So in this PR we set out to make this possible first, by transforming all current queues to be intrusive lists of permits. Permits are already linked into an intrusive list, to allow for enumerating all existing permits. We use these existing hooks to link the permits into the appropriate queue, and back to `_permit_list` when they are not in any special queue. To make this possible we first have to make all lists store naked permits, moving all auxiliary data fields currently stored in wrappers like `entry` into the permit itself. With this, all queues and lists in the semaphore are intrusive lists, storing permits directly, which has the following implications:
* queues no longer take extra memory, as all of them are intrusive
* permits are completely self-sufficient w.r.t to queuing: code can queue or dequeue permits just with a reference to a permit at hand, no other wrapper, iterator, pointer, etc. is necessary.
* queues don't keep permits alive anymore; destroying a permit will automatically unlink it from the respective queue, although this might lead to use-after-free. Not a problem in practice, only one code-path (`reader_concurrenc_semaphore::with_permit()`) had to be adjusted.
After all that extensive preparations, we can now handle the case of evicting a reader which is queued on memory.
Fixes: #12700Closes#12777
* github.com:scylladb/scylladb:
reader_concurrency_semaphore: handle reader blocked on memory becoming inactive
reader_concurrency_semaphore: move _permit_list next to the other lists
reader_permit: evict inactive read on timeout
reader_concurrency_semaphore: move inactive_read to .cc
reader_concurrency_semaphore: store permits in _inactive_reads
reader_concurrency_semaphore: inactive_read: de-inline more methods
reader_concurrency_semaphore: make _ready_list intrusive
reader_permit: add wait_for_execution state
reader_concurrency_semaphore: make wait lists intrusive
reader_concurrency_semaphore: move most wait_queue methods out-of-line
reader_concurrency_semaphore: store permits directly in queues
reader_permit: introduce (private) operator * and ->
reader_concurrency_semaphore: remove redundant waiters() member
reader_concurrency_semaphore: add waiters counter
reader_permit: use check_abort() for timeout
reader_concurrency_semaphore: maybe_dump_permit_diagnostics(): remove permit list param
reader_concurrency_semaphroe: make foreach_permit() const
reader_permit: add get_schema() and get_op_name() accessors
reader_concurrency_semaphore: mark maybe_dump_permit_diagnostics as noexcept
I've no idea why the quotes are there at all, it works even without
them. However, with quotes gdb-13 fails to find the _all_threads static
thread-local variable _unless_ it's printed with gdb "p" command
beforehand.
fixes: #13125
Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>
Closes#13132
Use it to keep track of all permits that are currently waiting on
something: admission, memory or execution.
Currently we keep track of size, by adding up the result of size() of
the various queues. In future patches we are going to change the queues
such that they will not have constant time size anymore, move to an
explicit counter in preperation to that.
Another change this commit makes is to also include ready list entries
in this counter. Permits in the ready list are also waiters, they wait
to be executed. Soon we will have a separate wait state for this too.
Since 5c0f9a8180 ("mutation_partition: Switch cache of
rows onto B-tree") it's no longer in use, except in some
performance test, so remove it.
Although scylla-gdb.py is sometimes used with older releases,
it's so outdated we can remove it from there too.
Closes#12868
This phrase is inaccurate and unnecessary. We know all lines in the
printout are for reads and they are semaphores: no need to repeat this
information on each line.
Example:
Read Concurrency Semaphores:
read: 0/100, 0/ 41901096, queued: 0
streaming: 0/ 10, 0/ 41901096, queued: 0
system: 0/ 10, 0/ 41901096, queued: 0
Closes#12633
Sets the current schema to be used by schema-aware commands.
Setting the schema allows some commands and printers to interpret
schema-dependent objects and present them in a more friendly form.
Some commands require schema to work, for example to sort keys, and
will fail otherwise.
A possibly blocking request for more memory. If the collective memory
consumption of all reads goes above
$serialize_limit_multiplier * $memory_limit this request will block for
all but one reader (the first requester). Until this situation is
resolved, that is until memory stays above the above explained limit,
only this one reader is allowed to make progress. This should help reign
in the memory consumption of reads in a situation where their memory
consumption used to baloon without constraints before.
Retrieves the configuration item with the given name and prints its
value as well as its metadata.
Example:
(gdb) scylla get-config-value compaction_static_shares
value: 100, type: "float", source: SettingsFile, status: Used, live: MustRestart
Closes#12362
* github.com:scylladb/scylladb:
scylla-gdb.py: add scylla get-config-value gdb command
scylla-gdb.py: extract $downcast_vptr logic to standalone method
test: scylla-gdb/run: improve diagnostics for failed tests
Retrieves the configuration item with the given name and prints its
value as well as its metadata.
Example:
(gdb) scylla get-config-value compaction_static_shares
value: 100, type: "float", source: SettingsFile, status: Used, live: MustRestart
When a class inherits from multiple virtual base classes, pointers to
instances of this class via one of its base classes, might point to
somewhere into the object, not at its beginning. Therefore, the simple
method employed currently by $downcast_vptr() of casting the provided
pointer to the type extracted from the vtable name fails. Instead when
this situation is detected (detectable by observing that the symbol name
of the partial vtable is not to an offset of +16, but larger),
$downcast_vptr() will iterate over the base classes, adjusting the
pointer with their offsets, hoping to find the true start of the object.
In the one instance I tested this with, this method worked well.
At the very least, the method will now yield a null pointer when it
fails, instead of a badly casted object with corrupt content (which the
developer might or might not attribute to the bad cast).
Closes#11892
Currently, to_string() recursively calls itself for engaged optionals.
Eliminate it. Also, use the std_optional wrapper instead of accessing
std::optional internals directly.
Scylla fiber uses a crude method of scanning inbound and outbound
references to/from other task objects of recognized type. This method
cannot detect user instantiated promise<> objects. Add a note about this
to the printout, so users are beware of this.
We collect already seen tasks in a set to be able to detect perceived
task loops and stop when one is seen. Initialize this set with the
starting task, so if it forms a loop, we won't repeat it in the trace
before cutting the loop.
Currently there is two loops and a separate line printing the starting
task, all duplicating the formatting logic. Define a method for it and
use it in all 3 places instead.
Shard boundaries can be crossed in one direction currently: when looking
for waiters on a task, but not in the other direction (looking for
waited-on tasks). This patch fixes that.
Currently seastar threads end any attempt to follow waited-on-futures.
Seastar threads need special handling because it allocates the wake up
task on its stack. This patch adds this special handling.
scylla_ptr.analyze() switches to the thread the analyzed object lives
on, but forgets to switch back. This was very annoying as any commands
using it (which is a bunch of them) were prone to suddenly and
unexpectedly switching threads.
This patch makes sure that the original thread context is switched back
to after analyzing the pointer.
Rename to scylla tables. Less typing and more up-to-date.
By default it now only lists tables from local shard. Added flag -a
which brings back old behaviour (lists on all shards).
Added -u (only list user tables) and -k (list tables of provided
keyspace only) filtering options.
The lsa-segment command tries to walk LSA segment objects by decoding
their descriptors and (!) object sizes as well. Some objects in LSA have
dynamic sizes, i.e. those depending on the object contents. The script
tries to drill down the object internals to get this size, but bad news
is that nowadays there are many dynamic objects that are not covered.
Once stepped upon unsupported object, scylla-gdb likely stops because
the "next" descriptor happens to be in the middle of the object and its
parsing throws.
This patch fixes this by taking advantage of the virtual size() call of
the migrate_fn_type all LSA objects are linked with (indirectly). It
gets the migrator object, the LSA object itself and calls
((migrate_fn_type*)<migrator_ptr>)->size((const void*)<object_ptr>)
with gdb. The evaluated value is the live dynamic size of the object.
fixes: #11792
refs: #2455
Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>
Closes#11847
The "virtual dirty" term is not very informative. "Virtual" means
"not real", but it doesn't say in which way it isn't real.
In this case, virtual dirty refers to real dirty memory, minus
the portion of memtables that has been written to disk (but not
yet sealed - in that case it would not be dirty in the first
place).
I chose to call "the portion of memtables that has been written
to disk" as "spooled memory". At least the unique term will cause
people to look it up and may be easier to remember. From that
we have "unspooled memory".
I plan to further change the accounting to account for spooled memory
rather than unspooled, as that is a more natural term, but that is left
for later.
The documentation, config item, and metrics are adjusted. The config
item is practically unused so it isn't worth keeping compatibility here.
Before 95f31f37c1 ("Merge 'dirty_memory_manager: simplify
region_group' from Avi Kivity"), we had two region_group
objects, one _real_region_group and another _virtual_region_group,
each with a set of "soft" and "hard" limits and related functions
and members.
In 95f31f37c1, we merged _real_region_group into _virtual_region_group,
but unfortunately the _real_region_group members received the "hard"
prefix when they got merged. This overloads the meaning of "hard" -
is it related to soft/hard limit or is it related to the real/virtual
distinction?
This patch applied some renaming to restore consistency. Anything
that came from _virtual_region_group now has "virtual" in its name.
Anything that came from _real_region_group now has "real" in its name.
The terms are still pretty bad but at least they are consistent.
The two classes always have a 1:1 or 0:1 relationship, and
so we can just move all the members of memory_hard_limit
into region_group, with the functions that track the relationship
(memory_hard_limit::{add,del}()) removed.
The 0:1 relationship is maintained by initializing the
hard limit parameter with std::numeric_limits<size_t>::max().
The _hard_total_memory variable is always checked if it is
greater than this parameter in order to do anything, and
with this default it can never be.
