看官方文档已经对落盘的读取进行了优化：https://docs.pingcap.com/zh/tidb/stable/release-7.1.1#:~:text=优化与落盘相关的%20chunk%20读取的性能
对应的ISSUE：Implement a fast row container reader to dump rows from disk · Issue #45125 · pingcap/tidb · GitHub
可是相同的数据量在7.1.1版本中执行发现落盘后，效率还是很低下。
mysql> set tidb_distsql_scan_concurrency=1;
Query OK, 0 rows affected (0.00 sec)
mysql> set tidb_mem_quota_query=209715200;
Query OK, 0 rows affected (0.00 sec)
mysql> explain analyze select * from customer order by C_COMMENT desc, C_ACCTBAL asc;
+-------------------------+------------+---------+-----------+----------------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+-----------------------------------------------------------+----------+----------+
| id | estRows | actRows | task | access object | execution info | operator info | memory | disk |
+-------------------------+------------+---------+-----------+----------------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+-----------------------------------------------------------+----------+----------+
| Sort_4 | 1500000.00 | 1500000 | root | | time:34.6s, loops:1466, RU:5061.368437 | tpch10.customer.c_comment:desc, tpch10.customer.c_acctbal | 189.3 MB | 204.9 MB |
| └─TableReader_8 | 1500000.00 | 1500000 | root | | time:1.52s, loops:1468, cop_task: {num: 54, max: 74.9ms, min: 817µs, avg: 29.1ms, p95: 63.2ms, max_proc_keys: 50144, p95_proc_keys: 50144, tot_proc: 1.17s, tot_wait: 8.07ms, rpc_num: 54, rpc_time: 1.57s, copr_cache_hit_ratio: 0.00, build_task_duration: 13.6µs, max_distsql_concurrency: 1} | data:TableFullScan_7 | 22.5 MB | N/A |
| └─TableFullScan_7 | 1500000.00 | 1500000 | cop[tikv] | table:customer | tikv_task:{proc max:39ms, min:0s, avg: 13.1ms, p80:23ms, p95:32ms, iters:1678, tasks:54}, scan_detail: {total_process_keys: 1500000, total_process_keys_size: 305225771, total_keys: 1500054, get_snapshot_time: 1.24ms, rocksdb: {delete_skipped_count: 217344, key_skipped_count: 1717344, block: {cache_hit_count: 7743}}} | keep order:false | N/A | N/A |
+-------------------------+------------+---------+-----------+----------------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+-----------------------------------------------------------+----------+----------+
3 rows in set (34.58 sec)
mysql> select version();
+--------------------+
| version() |
+--------------------+
| 5.7.25-TiDB-v7.1.1 |
+--------------------+
1 row in set (0.00 sec)
看pprof像是GC的问题：
(pprof) top
Showing nodes accounting for 5780ms, 60.97% of 9480ms total
Dropped 256 nodes (cum <= 47.40ms)
Showing top 10 nodes out of 141
flat flat% sum% cum cum%
2400ms 25.32% 25.32% 2400ms 25.32% runtime.memclrNoHeapPointers
1210ms 12.76% 38.08% 1210ms 12.76% runtime/internal/syscall.Syscall6
490ms 5.17% 43.25% 490ms 5.17% runtime.(*fixalloc).alloc
430ms 4.54% 47.78% 940ms 9.92% runtime.sweepone
260ms 2.74% 50.53% 280ms 2.95% runtime.findObject
260ms 2.74% 53.27% 4880ms 51.48% runtime.mallocgc
210ms 2.22% 55.49% 800ms 8.44% runtime.scanobject
180ms 1.90% 57.38% 200ms 2.11% runtime.writeHeapBits.flush
170ms 1.79% 59.18% 170ms 1.79% hash/crc32.ieeeCLMUL
170ms 1.79% 60.97% 170ms 1.79% runtime.futex
(pprof) tree
Showing nodes accounting for 8.33s, 87.87% of 9.48s total
Dropped 256 nodes (cum <= 0.05s)
Showing top 80 nodes out of 141
----------------------------------------------------------+-------------
flat flat% sum% cum cum% calls calls% + context
----------------------------------------------------------+-------------
2.40s 100% | runtime.mallocgc
2.40s 25.32% 25.32% 2.40s 25.32% | runtime.memclrNoHeapPointers
----------------------------------------------------------+-------------
1.18s 97.52% | syscall.RawSyscall6
1.21s 12.76% 38.08% 1.21s 12.76% | runtime/internal/syscall.Syscall6
----------------------------------------------------------+-------------
0.46s 93.88% | runtime.(*mheap).allocSpan
0.03s 6.12% | runtime.systemstack
0.49s 5.17% 43.25% 0.49s 5.17% | runtime.(*fixalloc).alloc
----------------------------------------------------------+-------------
0.94s 100% | runtime.bgsweep
0.43s 4.54% 47.78% 0.94s 9.92% | runtime.sweepone
0.41s 43.62% | runtime.(*sweepLocked).sweep
0.03s 3.19% | runtime.(*spanSet).pop
0.03s 3.19% | runtime.(*sweepLocker).tryAcquire
----------------------------------------------------------+-------------
0.28s 100% | runtime.scanobject
0.26s 2.74% 50.53% 0.28s 2.95% | runtime.findObject
----------------------------------------------------------+-------------
4.54s 93.03% | runtime.makeslice
0.27s 5.53% | runtime.newobject
0.07s 1.43% | github.com/pingcap/tidb/util/checksum.(*Reader).ReadAt
0.26s 2.74% 53.27% 4.88s 51.48% | runtime.mallocgc
2.40s 49.18% | runtime.memclrNoHeapPointers
1.19s 24.39% | runtime.(*mcache).nextFree
0.43s 8.81% | runtime.mProf_Malloc
0.28s 5.74% | runtime.(*mcache).allocLarge
0.10s 2.05% | runtime.heapBitsSetType
0.10s 2.05% | runtime.nextFreeFast (inline)
0.03s 0.61% | runtime.systemstack
----------------------------------------------------------+-------------
0.79s 98.75% | runtime.gcDrain
0.01s 1.25% | runtime.systemstack
0.21s 2.22% 55.49% 0.80s 8.44% | runtime.scanobject
0.28s 35.00% | runtime.findObject
0.19s 23.75% | runtime.greyobject
0.08s 10.00% | runtime.heapBitsForAddr
----------------------------------------------------------+-------------
0.11s 55.00% | runtime.(*mcentral).cacheSpan
0.06s 30.00% | runtime.(*mcache).allocLarge
0.03s 15.00% | runtime.heapBitsSetType
0.18s 1.90% 57.38% 0.20s 2.11% | runtime.writeHeapBits.flush
----------------------------------------------------------+-------------
0.17s 100% | hash/crc32.archUpdateIEEE
0.17s 1.79% 59.18% 0.17s 1.79% | hash/crc32.ieeeCLMUL
----------------------------------------------------------+-------------
0.11s 64.71% | runtime.unlock2
0.04s 23.53% | runtime.systemstack
0.17s 1.79% 60.97% 0.17s 1.79% | runtime.futex
----------------------------------------------------------+-------------
0.12s 92.31% | github.com/pingcap/tidb/util/chunk.appendCellByCell
0.01s 7.69% | github.com/pingcap/tidb/util/checksum.(*Reader).ReadAt
0.13s 1.37% 62.34% 0.13s 1.37% | runtime.memmove
----------------------------------------------------------+-------------
0.05s 41.67% | runtime.(*consistentHeapStats).acquire (inline)
0.05s 41.67% | runtime.(*consistentHeapStats).release (inline)
0.02s 16.67% | runtime.(*spanSet).pop (inline)
0.12s 1.27% 63.61% 0.12s 1.27% | runtime/internal/atomic.(*Uint32).Add
----------------------------------------------------------+-------------
0.10s 100% | github.com/pingcap/tidb/util/chunk.genCmpStringFunc.func1 (inline)
0.10s 1.05% 64.66% 0.10s 1.05% | github.com/pingcap/tidb/util/chunk.(*Column).IsNull
----------------------------------------------------------+-------------
0.22s 100% | github.com/pingcap/tidb/util/chunk.(*Chunk).AppendPartialRow
0.10s 1.05% 65.72% 0.22s 2.32% | github.com/pingcap/tidb/util/chunk.appendCellByCell
0.12s 54.55% | runtime.memmove
----------------------------------------------------------+-------------
0.41s 97.62% | runtime.sweepone
0.01s 2.38% | runtime.(*mcentral).cacheSpan
0.10s 1.05% 66.77% 0.42s 4.43% | runtime.(*sweepLocked).sweep
0.24s 57.14% | runtime.systemstack
0.02s 4.76% | runtime.unlock2
0.01s 2.38% | runtime.(*consistentHeapStats).acquire
0.01s 2.38% | runtime.(*consistentHeapStats).release
----------------------------------------------------------+-------------
0.10s 100% | runtime.mallocgc (inline)
0.10s 1.05% 67.83% 0.10s 1.05% | runtime.nextFreeFast
----------------------------------------------------------+-------------
0.15s 57.69% | runtime.pcdatavalue
0.11s 42.31% | runtime.gentraceback
0.10s 1.05% 68.88% 0.26s 2.74% | runtime.pcvalue
0.12s 46.15% | runtime.step
----------------------------------------------------------+-------------
0.12s 100% | runtime.pcvalue
0.10s 1.05% 69.94% 0.12s 1.27% | runtime.step
----------------------------------------------------------+-------------
0.07s 87.50% | runtime.(*mheap).freeSpanLocked
0.01s 12.50% | runtime.(*mheap).allocSpan
0.08s 0.84% 70.78% 0.08s 0.84% | runtime.(*pallocBits).summarize
----------------------------------------------------------+-------------
0.07s 100% | github.com/pingcap/tidb/types.CompareString (inline)
0.07s 0.74% 71.52% 0.07s 0.74% | github.com/pingcap/tidb/util/collate.truncateTailingSpace
----------------------------------------------------------+-------------
0.09s 100% | runtime.(*mcache).refill
0.07s 0.74% 72.26% 0.09s 0.95% | runtime.(*spanSet).push
----------------------------------------------------------+-------------
0.04s 57.14% | runtime.(*mcentral).cacheSpan
0.03s 42.86% | runtime.sweepone
0.07s 0.74% 73.00% 0.07s 0.74% | runtime.(*sweepLocker).tryAcquire
----------------------------------------------------------+-------------
0.08s 100% | runtime.scanobject
0.07s 0.74% 73.73% 0.08s 0.84% | runtime.heapBitsForAddr
----------------------------------------------------------+-------------
0.07s 87.50% | runtime.greyobject (inline)
0.01s 12.50% | runtime.(*mheap).freeSpanLocked (inline)
0.07s 0.74% 74.47% 0.08s 0.84% | runtime.pageIndexOf
----------------------------------------------------------+-------------
0.06s 100% | runtime.(*mcache).refill (inline)
0.06s 0.63% 75.11% 0.06s 0.63% | runtime.(*mcentral).partialSwept
----------------------------------------------------------+-------------
0.06s 100% | runtime.(*mheap).initSpan
0.06s 0.63% 75.74% 0.06s 0.63% | runtime.(*mspan).init
----------------------------------------------------------+-------------
0.19s 100% | runtime.scanobject
0.06s 0.63% 76.37% 0.19s 2.00% | runtime.greyobject
0.07s 36.84% | runtime.pageIndexOf (inline)
0.05s 26.32% | runtime.(*gcWork).putFast (inline)
----------------------------------------------------------+-------------
1.92s 100% | io.(*SectionReader).Read
0.05s 0.53% 76.90% 1.92s 20.25% | github.com/pingcap/tidb/util/checksum.(*Reader).ReadAt
1.49s 77.60% | os.(*File).ReadAt
0.26s 13.54% | hash/crc32.update
0.07s 3.65% | runtime.mallocgc
0.01s 0.52% | runtime.memmove
----------------------------------------------------------+-------------
0.05s 100% | hash/crc32.archUpdateIEEE (inline)
0.05s 0.53% 77.43% 0.05s 0.53% | hash/crc32.simpleUpdate
----------------------------------------------------------+-------------
0.05s 100% | runtime.greyobject (inline)
0.05s 0.53% 77.95% 0.05s 0.53% | runtime.(*gcWork).putFast
----------------------------------------------------------+-------------
1.15s 100% | runtime.(*mcache).nextFree
0.05s 0.53% 78.48% 1.15s 12.13% | runtime.(*mcache).refill
0.87s 75.65% | runtime.(*mcentral).cacheSpan
0.09s 7.83% | runtime.(*spanSet).push
0.06s 5.22% | runtime.(*mcentral).partialSwept (inline)
0.03s 2.61% | runtime.(*consistentHeapStats).release
0.01s 0.87% | runtime.(*consistentHeapStats).acquire
----------------------------------------------------------+-------------
0.21s 100% | runtime.systemstack
0.05s 0.53% 79.01% 0.21s 2.22% | runtime.(*mheap).freeSpanLocked
0.07s 33.33% | runtime.(*pallocBits).summarize
0.02s 9.52% | runtime.(*consistentHeapStats).acquire
0.02s 9.52% | runtime.(*consistentHeapStats).release
0.01s 4.76% | runtime.pageIndexOf (inline)
----------------------------------------------------------+-------------
0.16s 100% | runtime.(*mheap).allocSpan
0.05s 0.53% 79.54% 0.16s 1.69% | runtime.(*mheap).initSpan
0.06s 37.50% | runtime.(*mspan).init
----------------------------------------------------------+-------------
1.96s 100% | io.ReadAtLeast
0.04s 0.42% 79.96% 1.96s 20.68% | io.(*SectionReader).Read
1.92s 97.96% | github.com/pingcap/tidb/util/checksum.(*Reader).ReadAt
----------------------------------------------------------+-------------
1.49s 100% | github.com/pingcap/tidb/util/checksum.(*Reader).ReadAt
0.04s 0.42% 80.38% 1.49s 15.72% | os.(*File).ReadAt
1.45s 97.32% | os.(*File).pread (inline)
----------------------------------------------------------+-------------
0.87s 100% | runtime.(*mcache).refill
0.04s 0.42% 80.80% 0.87s 9.18% | runtime.(*mcentral).cacheSpan
0.63s 72.41% | runtime.(*mheap).alloc
0.11s 12.64% | runtime.writeHeapBits.flush
0.04s 4.60% | runtime.(*sweepLocker).tryAcquire
0.02s 2.30% | runtime.(*spanSet).pop
0.01s 1.15% | runtime.(*sweepLocked).sweep
----------------------------------------------------------+-------------
0.80s 100% | runtime.(*mheap).alloc.func1
0.04s 0.42% 81.22% 0.80s 8.44% | runtime.(*mheap).allocSpan
0.46s 57.50% | runtime.(*fixalloc).alloc
0.16s 20.00% | runtime.(*mheap).initSpan
0.09s 11.25% | runtime.unlock2
0.01s 1.25% | runtime.(*pallocBits).summarize
----------------------------------------------------------+-------------
0.09s 100% | syscall.Syscall6
0.04s 0.42% 81.65% 0.09s 0.95% | runtime.exitsyscall
----------------------------------------------------------+-------------
0.36s 100% | runtime.systemstack
0.04s 0.42% 82.07% 0.36s 3.80% | runtime.gentraceback
0.17s 47.22% | runtime.pcdatavalue
0.11s 30.56% | runtime.pcvalue
----------------------------------------------------------+-------------
0.10s 100% | runtime.mallocgc
0.04s 0.42% 82.49% 0.10s 1.05% | runtime.heapBitsSetType
0.03s 30.00% | runtime.writeHeapBits.flush
----------------------------------------------------------+-------------
0.04s 50.00% | runtime.systemstack
0.01s 12.50% | runtime.gcDrain
0.04s 0.42% 82.91% 0.08s 0.84% | runtime.lock2
----------------------------------------------------------+-------------
4.70s 100% | github.com/pingcap/tidb/executor.(*ExplainExec).executeAnalyzeExec
0.03s 0.32% 83.23% 4.70s 49.58% | github.com/pingcap/tidb/util/chunk.(*diskFormatRow).toRow
2.72s 57.87% | runtime.makeslice
1.80s 38.30% | github.com/pingcap/tidb/util/chunk.newFixedLenColumn (inline)
0.14s 2.98% | runtime.newobject
----------------------------------------------------------+-------------
0.25s 100% | hash/crc32.update
0.03s 0.32% 83.54% 0.25s 2.64% | hash/crc32.archUpdateIEEE
0.17s 68.00% | hash/crc32.ieeeCLMUL
0.05s 20.00% | hash/crc32.simpleUpdate (inline)
----------------------------------------------------------+-------------
1.19s 100% | runtime.mallocgc
0.03s 0.32% 83.86% 1.19s 12.55% | runtime.(*mcache).nextFree
1.15s 96.64% | runtime.(*mcache).refill
----------------------------------------------------------+-------------
2.72s 59.52% | github.com/pingcap/tidb/util/chunk.(*diskFormatRow).toRow
1.72s 37.64% | github.com/pingcap/tidb/util/chunk.newFixedLenColumn
0.13s 2.84% | github.com/pingcap/tidb/util/chunk.(*rowInDisk).ReadFrom
0.03s 0.32% 84.18% 4.57s 48.21% | runtime.makeslice
4.54s 99.34% | runtime.mallocgc
----------------------------------------------------------+-------------
0.25s 100% | github.com/pingcap/tidb/executor.(*multiWayMerge).Less
0.02s 0.21% 84.39% 0.25s 2.64% | github.com/pingcap/tidb/executor.(*SortExec).lessRow
0.23s 92.00% | github.com/pingcap/tidb/util/chunk.genCmpStringFunc.func1
----------------------------------------------------------+-------------
0.03s 60.00% | runtime.sweepone
0.02s 40.00% | runtime.(*mcentral).cacheSpan
0.02s 0.21% 84.60% 0.05s 0.53% | runtime.(*spanSet).pop
0.02s 40.00% | runtime/internal/atomic.(*Uint32).Add (inline)
----------------------------------------------------------+-------------
0.17s 100% | runtime.gentraceback
0.02s 0.21% 84.81% 0.17s 1.79% | runtime.pcdatavalue
0.15s 88.24% | runtime.pcvalue
----------------------------------------------------------+-------------
1.36s 100% | syscall.pread
0.02s 0.21% 85.02% 1.36s 14.35% | syscall.Syscall6
1.17s 86.03% | syscall.RawSyscall6
0.09s 6.62% | runtime.exitsyscall
0.08s 5.88% | runtime.entersyscall
----------------------------------------------------------+-------------
1.38s 100% | internal/poll.(*FD).Pread
0.02s 0.21% 85.23% 1.38s 14.56% | syscall.pread
1.36s 98.55% | syscall.Syscall6
----------------------------------------------------------+-------------
0.27s 100% | container/heap.Fix
0.01s 0.11% 85.34% 0.27s 2.85% | container/heap.down
0.26s 96.30% | github.com/pingcap/tidb/executor.(*multiWayMerge).Less
----------------------------------------------------------+-------------
0.26s 100% | container/heap.down
0.01s 0.11% 85.44% 0.26s 2.74% | github.com/pingcap/tidb/executor.(*multiWayMerge).Less
0.25s 96.15% | github.com/pingcap/tidb/executor.(*SortExec).lessRow
----------------------------------------------------------+-------------
0.08s 100% | github.com/pingcap/tidb/util/chunk.genCmpStringFunc.func1
0.01s 0.11% 85.55% 0.08s 0.84% | github.com/pingcap/tidb/types.CompareString
0.07s 87.50% | github.com/pingcap/tidb/util/collate.truncateTailingSpace (inline)
----------------------------------------------------------+-------------
0.23s 100% | github.com/pingcap/tidb/executor.(*ExplainExec).executeAnalyzeExec
0.01s 0.11% 85.65% 0.23s 2.43% | github.com/pingcap/tidb/util/chunk.(*Chunk).AppendPartialRow
0.22s 95.65% | github.com/pingcap/tidb/util/chunk.appendCellByCell
----------------------------------------------------------+-------------
0.44s 100% | github.com/pingcap/tidb/executor.(*ExplainExec).executeAnalyzeExec
0.01s 0.11% 85.76% 0.44s 4.64% | github.com/pingcap/tidb/util/chunk.(*ListInDisk).getOffset
0.39s 88.64% | io.ReadAtLeast
0.04s 9.09% | runtime.newobject
----------------------------------------------------------+-------------
1.72s 100% | github.com/pingcap/tidb/executor.(*ExplainExec).executeAnalyzeExec
0.01s 0.11% 85.86% 1.72s 18.14% | github.com/pingcap/tidb/util/chunk.(*rowInDisk).ReadFrom
1.58s 91.86% | io.ReadAtLeast
0.13s 7.56% | runtime.makeslice
----------------------------------------------------------+-------------
0.23s 100% | github.com/pingcap/tidb/executor.(*SortExec).lessRow
0.01s 0.11% 85.97% 0.23s 2.43% | github.com/pingcap/tidb/util/chunk.genCmpStringFunc.func1
0.10s 43.48% | github.com/pingcap/tidb/util/chunk.(*Column).IsNull (inline)
0.08s 34.78% | github.com/pingcap/tidb/types.CompareString
----------------------------------------------------------+-------------
1.80s 100% | github.com/pingcap/tidb/util/chunk.(*diskFormatRow).toRow (inline)
0.01s 0.11% 86.08% 1.80s 18.99% | github.com/pingcap/tidb/util/chunk.newFixedLenColumn
1.72s 95.56% | runtime.makeslice
0.07s 3.89% | runtime.newobject
----------------------------------------------------------+-------------
0.26s 100% | github.com/pingcap/tidb/util/checksum.(*Reader).ReadAt
0.01s 0.11% 86.18% 0.26s 2.74% | hash/crc32.update
0.25s 96.15% | hash/crc32.archUpdateIEEE
----------------------------------------------------------+-------------
1.44s 100% | os.(*File).pread
0.01s 0.11% 86.29% 1.44s 15.19% | internal/poll.(*FD).Pread
1.38s 95.83% | syscall.pread
----------------------------------------------------------+-------------
1.58s 80.20% | github.com/pingcap/tidb/util/chunk.(*rowInDisk).ReadFrom
0.39s 19.80% | github.com/pingcap/tidb/util/chunk.(*ListInDisk).getOffset
0.01s 0.11% 86.39% 1.97s 20.78% | io.ReadAtLeast
1.96s 99.49% | io.(*SectionReader).Read
----------------------------------------------------------+-------------
1.45s 100% | os.(*File).ReadAt (inline)
0.01s 0.11% 86.50% 1.45s 15.30% | os.(*File).pread
1.44s 99.31% | internal/poll.(*FD).Pread
----------------------------------------------------------+-------------
0.02s 33.33% | runtime.(*mcache).allocLarge
0.02s 33.33% | runtime.(*mheap).freeSpanLocked
0.01s 16.67% | runtime.(*mcache).refill
0.01s 16.67% | runtime.(*sweepLocked).sweep
0.01s 0.11% 86.60% 0.06s 0.63% | runtime.(*consistentHeapStats).acquire
0.05s 83.33% | runtime/internal/atomic.(*Uint32).Add (inline)
----------------------------------------------------------+-------------
0.03s 50.00% | runtime.(*mcache).refill
0.02s 33.33% | runtime.(*mheap).freeSpanLocked
0.01s 16.67% | runtime.(*sweepLocked).sweep
0.01s 0.11% 86.71% 0.06s 0.63% | runtime.(*consistentHeapStats).release
0.05s 83.33% | runtime/internal/atomic.(*Uint32).Add (inline)
----------------------------------------------------------+-------------
0.28s 100% | runtime.mallocgc
0.01s 0.11% 86.81% 0.28s 2.95% | runtime.(*mcache).allocLarge
0.19s 67.86% | runtime.(*mheap).alloc
0.06s 21.43% | runtime.writeHeapBits.flush
0.02s 7.14% | runtime.(*consistentHeapStats).acquire
----------------------------------------------------------+-------------
0.63s 76.83% | runtime.(*mcentral).cacheSpan
0.19s 23.17% | runtime.(*mcache).allocLarge
0.01s 0.11% 86.92% 0.82s 8.65% | runtime.(*mheap).alloc
0.81s 98.78% | runtime.systemstack
----------------------------------------------------------+-------------
0.81s 100% | runtime.systemstack
0.01s 0.11% 87.03% 0.81s 8.54% | runtime.(*mheap).alloc.func1
0.80s 98.77% | runtime.(*mheap).allocSpan
----------------------------------------------------------+-------------
0.01s 0.11% 87.13% 0.95s 10.02% | runtime.bgsweep
0.94s 98.95% | runtime.sweepone
----------------------------------------------------------+-------------
0.08s 100% | syscall.Syscall6
0.01s 0.11% 87.24% 0.08s 0.84% | runtime.entersyscall
0.01s 12.50% | runtime.systemstack
----------------------------------------------------------+-------------
0.87s 100% | runtime.systemstack
0.01s 0.11% 87.34% 0.87s 9.18% | runtime.gcDrain
0.79s 90.80% | runtime.scanobject
0.01s 1.15% | runtime.lock2
----------------------------------------------------------+-------------
0.43s 100% | runtime.mallocgc
0.01s 0.11% 87.45% 0.43s 4.54% | runtime.mProf_Malloc
0.41s 95.35% | runtime.systemstack
----------------------------------------------------------+-------------
0.14s 50.00% | github.com/pingcap/tidb/util/chunk.(*diskFormatRow).toRow
0.07s 25.00% | github.com/pingcap/tidb/util/chunk.newFixedLenColumn
0.04s 14.29% | github.com/pingcap/tidb/util/chunk.(*ListInDisk).getOffset
0.02s 7.14% | github.com/pingcap/tidb/executor.(*ExplainExec).executeAnalyzeExec
0.01s 0.11% 87.55% 0.28s 2.95% | runtime.newobject
0.27s 96.43% | runtime.mallocgc
----------------------------------------------------------+-------------
0.81s 33.33% | runtime.(*mheap).alloc
0.41s 16.87% | runtime.mProf_Malloc
0.24s 9.88% | runtime.(*sweepLocked).sweep
0.03s 1.23% | runtime.mallocgc
0.01s 0.41% | github.com/pingcap/tidb/executor.(*ExecStmt).next
0.01s 0.41% | runtime.entersyscall
0.01s 0.11% 87.66% 2.43s 25.63% | runtime.systemstack
0.87s 35.80% | runtime.gcDrain
0.81s 33.33% | runtime.(*mheap).alloc.func1
0.36s 14.81% | runtime.gentraceback
0.21s 8.64% | runtime.(*mheap).freeSpanLocked
0.04s 1.65% | runtime.futex
0.04s 1.65% | runtime.lock2
0.03s 1.23% | runtime.(*fixalloc).alloc
0.01s 0.41% | runtime.scanobject
0.01s 0.41% | runtime.unlock2
----------------------------------------------------------+-------------
0.09s 75.00% | runtime.(*mheap).allocSpan
0.02s 16.67% | runtime.(*sweepLocked).sweep
0.01s 8.33% | runtime.systemstack
0.01s 0.11% 87.76% 0.12s 1.27% | runtime.unlock2
0.11s 91.67% | runtime.futex
----------------------------------------------------------+-------------
1.17s 98.32% | syscall.Syscall6
0.01s 0.11% 87.87% 1.19s 12.55% | syscall.RawSyscall6
1.18s 99.16% | runtime/internal/syscall.Syscall6
----------------------------------------------------------+-------------
0.27s 100% | github.com/pingcap/tidb/executor.(*ExplainExec).executeAnalyzeExec
0 0% 87.87% 0.27s 2.85% | container/heap.Fix
0.27s 100% | container/heap.down
----------------------------------------------------------+-------------
0 0% 87.87% 7.45s 78.59% | github.com/pingcap/tidb/executor.(*ExecStmt).next
7.44s 99.87% | github.com/pingcap/tidb/executor.(*ExplainExec).Next
0.01s 0.13% | runtime.systemstack
----------------------------------------------------------+-------------
7.44s 100% | github.com/pingcap/tidb/executor.(*ExecStmt).next
0 0% 87.87% 7.44s 78.48% | github.com/pingcap/tidb/executor.(*ExplainExec).Next
7.44s 100% | github.com/pingcap/tidb/executor.(*ExplainExec).generateExplainInfo
----------------------------------------------------------+-------------
7.44s 100% | github.com/pingcap/tidb/executor.(*ExplainExec).generateExplainInfo
0 0% 87.87% 7.44s 78.48% | github.com/pingcap/tidb/executor.(*ExplainExec).executeAnalyzeExec
4.70s 63.17% | github.com/pingcap/tidb/util/chunk.(*diskFormatRow).toRow
1.72s 23.12% | github.com/pingcap/tidb/util/chunk.(*rowInDisk).ReadFrom
0.44s 5.91% | github.com/pingcap/tidb/util/chunk.(*ListInDisk).getOffset
0.27s 3.63% | container/heap.Fix
0.23s 3.09% | github.com/pingcap/tidb/util/chunk.(*Chunk).AppendPartialRow
0.02s 0.27% | runtime.newobject
----------------------------------------------------------+-------------
7.44s 100% | github.com/pingcap/tidb/executor.(*ExplainExec).Next
0 0% 87.87% 7.44s 78.48% | github.com/pingcap/tidb/executor.(*ExplainExec).generateExplainInfo
7.44s 100% | github.com/pingcap/tidb/executor.(*ExplainExec).executeAnalyzeExec