For debug purpose:
Add session variable skip_storage_engine_merge, when set to true, tables of aggregate key model and unique key model will be read as duplicate key model.
Add session variable skip_delete_predicate, when set to true, rows deleted with delete statement will be selected.
When FE send cancel rpc to BE, it does not notify the wait_for_start() thread, so that the fragment will be blocked and occupy the execution thread.
Add a max wait time for wait_for_start() thread. So that it will not block forever.
In some cases, when the user executes the query for the first time, an error of the exceeded mem limit will be reported, and the query will be successful only after the second execution.
This is because when the query is executed for the first time, the memory consumed by adding the page cache and other caches is recorded in the query mem tracker, hoping to unify the behavior of multiple queries.
A temporary solution, remove the hook of scanner thread, test clickbench q13
Before removing the scanner thread hook
Enable page cache: 3G for the first query, 3G for the tracker; 900M for the second query, 900M for the tracker.
Turn off page cache: 1.9G for the first query, 1.9G for the tracker; 900M for the second query, 900M for the tracker
After removing the scanner thread hook and fix MemTrackerLimiter::cache_consume_local bug
Enable page cache: 2916M for the first query, 1147M for the tracker; 979M for the second query, 1144M for the tracker
Turn off page cache: 1809M for the first query, 1147M for the tracker; 975M for the second query, 1145M for the tracker
TODO, a better solution is to track storage-related memory separately, in the scanner thread. Otherwise, it is impossible to know where the process memory grows when querying.
We have added logical project before, but to actually finish the prune to reduce the data IO, we need to add related supports in translator and BE.
This PR:
- add projections on each ExecNode in BE
- translate PhysicalProject into projections on PlanNode in FE
- do column prune on ScanNode in FE
Co-authored-by: HappenLee <happenlee@hotmail.com>
Copy most of profiles from VOlapScanNode and VOlapScanner to NewOlapScanNode and NewOlapScanner.
Fix some blocking bug of new scan framework.
TODO:
Memtracker
Opentelemetry spen
The new framework is still disabled by default, so it will not effect other feature.
Refactor TaggableLogger
Refactor status handling in agent task:
Unify log format in TaskWorkerPool
Pass Status to the top caller, and replace some OLAPInternalError with more detailed error message Status
Premature return with the opposite condition to reduce indention
Return the real process memory information when the process exceeds mem limit
Optimize the memory exceed limit log printing logic
process tracker does not participate in process memory limit.
There are currently many types of ScanNodes in Doris. And most of the logic of these ScanNodes is the same, including:
Runtime filter
Predicate pushdown
Scanner generation and scheduling
So I intend to unify the common logic of all ScanNodes.
Different data sources only need to implement different Scanners for data access.
So that the future optimization for scan can be applied to the scan of all data sources,
while also reducing the code duplication.
This PR mainly adds 4 new class:
VScanner
All Scanners' parent class. The subclasses can inherit this class to implement specific data access methods.
VScanNode
The unified ScanNode, and is responsible for common logic including RuntimeFilter, predicate pushdown, Scanner generation and scheduling.
ScannerContext
ScannerContext is responsible for recording the execution status
of a group of Scanners corresponding to a ScanNode.
Including how many scanners are being scheduled, and maintaining
a producer-consumer blocks queue between scanners and scan nodes.
ScannerContext is also the scheduling unit of ScannerScheduler.
ScannerScheduler schedules a ScannerContext at a time,
and submits the Scanners to the scanner thread pool for data scanning.
ScannerScheduler
Unified responsible for all Scanner scheduling tasks
Test:
This work is still in progress and default is disabled.
I tested it with jmeter with 50 concurrency, but currently the scanner is just return without data.
The QPS can reach about 9000.
I can't compare it to origin implement because no data is read for now. I will test it when new olap scanner is ready.
Co-authored-by: morningman <morningman@apache.org>
Disable Chunk Allocator in Vectorized Allocator, this will reduce memory cache.
For high concurrent queries, using Chunk Allocator with vectorized Allocator can reduce the impact of gperftools tcmalloc central lock.
Jemalloc or google tcmalloc have core cache, Chunk Allocator may no longer be needed after replacing gperftools tcmalloc.
The memory value automatically tracked by the tcmalloc hook in the DeltaWriter is smaller than the value recorded manually in the memtable, because the first 4096-byte Chunk requested by each MemPool when the memtable is initialized is not tracked to the DeltaWriter by the hook.
The values of the two are not equal, causing the mem_consumption() == _mem_table->memory_usage branch judgment to fail.
Currently, only the virtual memory used by the query can be tracked through the tcmalloc hook. When the memory is not fully used after the application, the recorded virtual memory will be larger than the physical memory.
At present, it is mainly because PODArray does not memset 0 when applying for memory, and blocks applied for through PODArray in places such as VOlapScanNode::_free_blocks are usually used for memory reuse and cannot be fully used.
