When the system MemAvailable is less than the warning water mark, or the memory used by the BE process exceeds the mem soft limit, run minor gc and try to release cache.
When the MemAvailable of the system is less than the low water mark, or the memory used by the BE process exceeds the mem limit, run fucc gc, try to release the cache, and start canceling from the query with the largest memory usage until the memory of mem_limit * 20% is released.
boost::stacktrace::stacktrace() has memory leak, so use glog internal func to print stacktrace.
The reason for the memory leak of boost::stacktrace is that a state is saved in the thread local of each thread but not actively released. The test found that each thread leaked about 100M after calling boost::stacktrace.
refer to:
boostorg/stacktrace#118boostorg/stacktrace#111
mem tracker can be logically divided into 4 layers: 1)process 2)type 3)query/load/compation task etc. 4)exec node etc.
type includes
enum Type {
GLOBAL = 0, // Life cycle is the same as the process, e.g. Cache and default Orphan
QUERY = 1, // Count the memory consumption of all Query tasks.
LOAD = 2, // Count the memory consumption of all Load tasks.
COMPACTION = 3, // Count the memory consumption of all Base and Cumulative tasks.
SCHEMA_CHANGE = 4, // Count the memory consumption of all SchemaChange tasks.
CLONE = 5, // Count the memory consumption of all EngineCloneTask. Note: Memory that does not contain make/release snapshots.
BATCHLOAD = 6, // Count the memory consumption of all EngineBatchLoadTask.
CONSISTENCY = 7 // Count the memory consumption of all EngineChecksumTask.
}
Object pointers are no longer saved between each layer, and the values of process and each type are periodically aggregated.
other fix:
In [fix](memtracker) Fix transmit_tracker null pointer because phamp is not thread safe #13528, I tried to separate the memory that was manually abandoned in the query from the orphan mem tracker. But in the actual test, the accuracy of this part of the memory cannot be guaranteed, so put it back to the orphan mem tracker again.
Previously, bthread_getspecific was called every time bthread local was used. In the test at #10823, it was found that frequent calls to bthread_getspecific had performance problems.
So a cache is implemented on pthread local based on the btls key, but the btls key cannot correctly sense bthread switching.
So, based on bthread_self to get the bthread id to implement the cache.
1. HttpServer threads allocate bytebuffer and put them into streamload pipe, but scanner thread release them with query tracker.
2. We can assume brpc allocate memory in doris thread.
Above problems leads to wrong result of memtracker.
The mem hook record tracker cannot guarantee that the final consumption is 0, nor can it guarantee that the memory alloc and free are recorded in a one-to-one correspondence.
In the life cycle of a memtable from insert to flush, the memory free of hook is more than that of alloc, resulting in tracker consumption less than 0.
In order to avoid the cumulative error of the upper load channel tracker, the memtable tracker consumption is reset to zero on destructor.
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.
1. Added flag exec_env_existed to indicate whether ExecEnv Instance is created.
2. ThreadMemTrackerMgr::add_tracker fail when USE_MEM_TRACKER=OFF, add USE_MEM_TRACKER compile option.
In some cases, query mem tracker does not exist in BE when transmit block. This will result in a null pointer for get query mem tracker in brpc transmit_block
1. Fix the memory leak. When the load task is canceled, the `IndexChannel` and `NodeChannel` mem trackers cannot be destructed in time.
2. Fix Load task being frequently canceled by oom and inaccurate `LoadChannel` mem tracker limit, and rewrite the variable name of `mem limit` in `LoadChannel`.
3. Fix core dump, when logout task mem tracker, phmap erase fails, resulting in repeated logout of the same tracker.
4. Fix the deadlock, when add_child_tracker mem limit exceeds, calling log_usage causes `_child_trackers_lock` deadlock.
5. Fix frequent log printing when thread mem tracker limit exceeds, which will affect readability and performance.
6. Optimize some details of mem tracker display.
1. Fix Lru Cache MemTracker consumption value is negative.
2. Fix compaction Cache MemTracker has no track.
3. Add USE_MEM_TRACKER compile option.
4. Make sure the malloc/free hook is not stopped at any time.
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.
1. fix track bthread
- Bthread, a high performance M:N thread library used by brpc. In Doris, a brpc server response runs on one bthread, possibly on multiple pthreads. Currently, MemTracker consumption relies on pthread local variables (TLS).
- This caused pthread TLS MemTracker confusion when switching pthread TLS MemTracker in brpc server response. So replacing pthread TLS with bthread TLS in the brpc server response saves the MemTracker.
Ref: 731730da85/docs/en/server.md (bthread-local)
2. fix track vectorized query
- Added track mmap. Currently, mmap allocates memory in many places of the vectorized execution engine.
- Refactored ThreadContext to avoid dependency conflicts and make it easier to debug.
- Fix some bugs.
In pr #8476, all memory usage of a process is recorded in the process mem tracker,
and all memory usage of a query is recorded in the query mem tracker,
and it is still necessary to manually call `transfer to` to track the cached memory size.
We hope to separate out more detailed memory usage based on Hook TCMalloc new/delete + TLS mem tracker.
In this pr, the more detailed mem tracker is switched to TLS, which automatically and accurately
counts more detailed memory usage than before.
Early Design Documentation: https://shimo.im/docs/DT6JXDRkdTvdyV3G
Implement a new way of memory statistics based on TCMalloc New/Delete Hook,
MemTracker and TLS, and it is expected that all memory new/delete/malloc/free
of the BE process can be counted.
The thread context saves some info about a working thread.
1. thread_id: Current thread id, Auto generated.
2. type: The type is a enum value indicating which type of task current thread is running.
For example: QUERY, LOAD, COMPACTION, ...
3. task id: A unique id to identify this task. maybe query id, load job id, etc.
Using gcc11 compiles thread_local variable on lower versions of GLIBC will report an error, see https://github.com/apache/incubator-doris/pull/7911
This is very difficult to solve, so kudu Class-scoped static thread local implementation was introduced.
Solve the above problem by Thread-scopedthread local + Class-scoped thread local.
See the comments for ThreadContextPtr for details.
