Before, refresh the TabletsChannel profile in the LoadChannelMgr refresh memory statistics thread
This means that enable_profile=false will refresh and have performance loss in stress test
TabletSink and LoadChannel in BE are M: N relationship,
Every once in a while LoadChannel will randomly return its own runtime profile to a TabletSink, so usually all LoadChannel runtime profiles are saved on each TabletSink, and the timeliness of the same LoadChannel profile saved on different TabletSinks is different, and each TabletSink will periodically send fe reports all the LoadChannel profiles saved by itself, and ensures to update the latest LoadChannel profile according to the timestamp.
Currently, there are some useless includes in the codebase. We can use a tool named include-what-you-use to optimize these includes. By using a strict include-what-you-use policy, we can get lots of benefits from it.
The current distribution model for Doris is as follows:
OlapTableSink seperate the original Block into serveral subblocks of each node(BE) by tablets distribution and distributes subblocks to storage engine of backends, then the storage engine will seperate the subblock into multiple tablets channel and each delta writer will handle partial of the block.
This model causes blocks to be split according to tablets, and the splitting process can be a relatively heavy operation. After splitting, the blocks are distributed to different DeltaWriters (Memtables) through RPCs to TabletChannels. The distribution operation on TabletChannels is also a relatively heavy operation. If the distribution property of the table is RANDOM distribution, then we have the opportunity to distribute the blocks according to the complete block during distribution. The advantage of doing so is to reduce memory copying and improve write locality, similar to appending the entire block to the memtable.
This optimze could save 10% ~ 20% CPU cost of RANDOM distribution table load when enable load_to_single_tablet
fmt::format dosen't support non-template object as args, even if it implements
`to_string()` or `operator<<`. so orignal code may cause `false` to be printed
instead of real cause of the failure. So to_string() need to be manually invoked.
Signed-off-by: freemandealer <freeman.zhang1992@gmail.com>
The result of load should be failed when all tablets delta writer failed to close on single node.
But the result returned to client is success.
The reason is that the committed tablets and error tablets are both empty, so publish will be success.
We should add it to error tablets when delta writer failed to close, then the transaction will be failed.
In the following case, data inconsistency would happen between multiple replicas
current delta writer only writes a few lines of data (which meas the write() method only called once)
writer failed when init()(which is called at the fist time we call write()), and current tablet is recorded in _broken_tablets
delta writer closed, and in the close() method, delta writer found it's not inited, treat such case as an empty load, it will try to init again, which would create an empty rowset.
tablet sink received the error report in rpc response, marked the replica as failed, but since the quorum replicas are succeed, so the following load commit operation will succeed.
FE send publish version task to each be, the one with empty rowset will publish version successfully.
We got 2 replica with data and 1 empty replica.
We should consider memory which are being flushed from memtable to disk when trying to reduce memory by flushing memtable. Otherwise, we might not release memory space as expected. (e.g. lots of large memtable is in flush, the reduce_mem_usage method picks some small memtables to flush, it can't release enough memory and also can generate lots of small segments, which can cause -238 error)
In the policy changed by PR #12716, when reaching the hard limit, there might be multiple threads can pick same LoadChannel and call reduce_mem_usage on same TabletsChannel. Although there's a lock and condition variable can prevent multiple threads to reduce mem usage concurrently, but they still can do same reduce-work on that channel multiple times one by one, even it's just reduced.
1. Remove single load channel mem limit, only use load channel mgr mem limit
2. Default load channel mgr mem limit from 50% to 80%
3. load channel mgr add soft mem limit. When the soft limit is exceeded, other threads will not hang, only current thread triggers flush
4. When exceed load channel mgr mem limit, find a load channel with the largest mem usage, continue to find a tablet channel with the largest mem usage, and try to flush 1/3 of the mem usage of this tablet channel.
In current policy, if mem-limit exceeded, load channel will pick tablets that consume most memory, but mem_consumption contains memory in flush, if some delta writer flushing a full memtable(default 200MB), the current memtable might be very small, we should avoid flush such memtable, which can generate a very small segment.
When the flush is triggered when the load channel exceeds the mem limit, if the flush fails, an error message is returned and the load is terminated.
Usually flush failure is -238 error code. Because the memtable is frequently flushed after the load channel exceeds the mem limit, the number of segments exceeds the max value.
During load process, the same operation are performed on all replicas such as sort and aggregation,
which are resource-intensive.
Concurrent data load would consume much CPU and memory resources.
It's better to perform write process (writing data into MemTable and then data flush) on single replica
and synchronize data files to other replicas before transaction finished.
* [Schema Change] support fast add/drop column (#49)
* [feature](schema-change) support fast schema change. coauthor: yixiutt
* [schema change] Using columns desc from fe to read data. coauthor: Lchangliang
* [feature](schema change) schema change optimize for add/drop columns.
1.add uniqueId field for class column.
2.schema change for add/drop columns directly update schema meta
Co-authored-by: yixiutt <yixiu@selectdb.com>
Co-authored-by: SWJTU-ZhangLei <1091517373@qq.com>
[Feature](schema change) fix write and add regression test (#69)
Co-authored-by: yixiutt <yixiu@selectdb.com>
[schema change] be ssupport that delete use newest schema
add delete regression test
fix regression case (#107)
tmp
[feature](schema change) light schema change exclude rollup and agg/uniq/dup key type.
[feature](schema change) fe olapTable maxUniqueId write in disk.
[feature](schema change) add rpc iface for sc add column.
[feature](schema change) add columnsDesc to TPushReq for ligtht sc.
resolve the deadlock when schema change (#124)
fix columns from fe don't has bitmap_index flag (#134)
add update/delete case
construct MATERIALIZED schema from origin schema when insert
fix not vectorized compaction coredump
use segment cache
choose newest schema by schema version when compaction (#182)
[bugfix](schema change) fix ligth schema change problem.
[feature](schema change) light schema change add alter job. (#1)
fix be ut
[bug] (schema change) unique drop key column should not light schema
change
[feature](schema change) add schema change regression-test.
fix regression test
[bugfix](schema change) fix multi alter clauses for light schema change. (#2)
[bugfix](schema change) fix multi clauses calculate column unique id (#3)
modify PushTask process (#217)
[Bugfix](schema change) fix jobId replay cause bdbje exception.
[bug](schema change) fix max col unique id repeatitive. (#232)
[optimize](schema change) modify pendingMaxColUniqueId generate rule.
fix compaction error
* fix be ut
* fix snapshot load core
fix unique_id error (#278)
[refact](fe) remove redundant code for light schema change. (#4)
[refact](fe) remove redundant code for light schema change. (#4)
format fe core
format be core
fix be ut
modify fe meta version
fix rebase error
flush schema into rowset_meta in old table
[refactor](schema change) refact fe light schema change. (#5)
delete the change of schemahash and support get max version schema
* modify for review
* fix be ut
* fix schema change test
1. Fix LoadTask, ChunkAllocator, TabletMeta, Brpc, the accuracy of memory track.
2. Modified some MemTracker names, deleted some unnecessary trackers, and improved readability.
3. More powerful MemTracker debugging capabilities.
4. Avoid creating TabletColumn temporary objects and improve BE startup time by 8%.
5. Fix some other details.
Currently, there are 2 status code in BE, one is common/Status.h,
and the other is olap/olap_define.h called OLAPStatus.
OLAPStatus is just an enum type, it is very simple and could not save many informations,
I will unify these code to common/Status.
