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TiDB Lightning Monitoring
Learn about the monitor configuration and monitoring metrics of TiDB Lightning.
/docs/dev/tidb-lightning/monitor-tidb-lightning/
/docs/dev/reference/tools/tidb-lightning/monitor/

TiDB Lightning Monitoring

tidb-lightning supports metrics collection via Prometheus. This document introduces the monitor configuration and monitoring metrics of TiDB Lightning.

Monitor configuration

If TiDB Lightning is manually installed, follow the instructions below.

The metrics of tidb-lightning can be gathered directly by Prometheus as long as it is discovered. You can set the metrics port in tidb-lightning.toml:

[lightning]
# HTTP port for debugging and Prometheus metrics pulling (0 to disable)
pprof-port = 8289

...

You need to configure Prometheus to make it discover the servers. For instance, you can directly add the server address to the scrape_configs section:

...
scrape_configs:
  - job_name: 'tidb-lightning'
    static_configs:
      - targets: ['192.168.20.10:8289']

Grafana dashboard

Grafana is a web interface to visualize Prometheus metrics as dashboards.

Row 1: Speed

Panels in first row

Panel Series Description
Import speed write from TiDB Lightning Speed of sending KVs from TiDB Lightning to TiKV Importer, which depends on each table's complexity
Import speed upload to tikv Total upload speed from TiKV Importer to all TiKV replicas
Chunk process duration Average time needed to completely encode one single data file

Sometimes the import speed will drop to zero allowing other parts to catch up. This is normal.

Row 2: Progress

Panels in second row

Panel Description
Import progress Percentage of data files encoded so far
Checksum progress Percentage of tables are verified to be imported successfully
Failures Number of failed tables and their point of failure, normally empty

Row 3: Resource

Panels in third row

Panel Description
Memory usage Amount of memory occupied by each service
Number of TiDB Lightning Goroutines Number of running goroutines used by TiDB Lightning
CPU% Number of logical CPU cores utilized by each service

Row 4: Quota

Panels in fourth row

Panel Series Description
Idle workers io Number of unused io-concurrency, normally close to configured value (default 5), and close to 0 means the disk is too slow
Idle workers closed-engine Number of engines which is closed but not yet cleaned up, normally close to index + table-concurrency (default 8), and close to 0 means TiDB Lightning is faster than TiKV Importer, which will cause TiDB Lightning to stall
Idle workers table Number of unused table-concurrency, normally 0 until the end of process
Idle workers index Number of unused index-concurrency, normally 0 until the end of process
Idle workers region Number of unused region-concurrency, normally 0 until the end of process
External resources KV Encoder Counts active KV encoders, normally the same as region-concurrency until the end of process
External resources Importer Engines Counts opened engine files, should never exceed the max-open-engines setting

Row 5: Read speed

Panels in fifth row

Panel Series Description
Chunk parser read block duration read block Time taken to read one block of bytes to prepare for parsing
Chunk parser read block duration apply worker Time elapsed to wait for an idle io-concurrency
SQL process duration row encode Time taken to parse and encode a single row
SQL process duration block deliver Time taken to send a block of KV pairs to TiKV Importer

If any of the duration is too high, it indicates that the disk used by TiDB Lightning is too slow or busy with I/O.

Row 6: Storage

Panels in sixth row

Panel Series Description
SQL process rate data deliver rate Speed of delivery of data KV pairs to TiKV Importer
SQL process rate index deliver rate Speed of delivery of index KV pairs to TiKV Importer
SQL process rate total deliver rate The sum of two rates above
Total bytes parser read size Number of bytes being read by TiDB Lightning
Total bytes data deliver size Number of bytes of data KV pairs already delivered to TiKV Importer
Total bytes index deliver size Number of bytes of index KV pairs already delivered to TiKV Importer
Total bytes storage_size / 3 Total size occupied by the TiKV cluster, divided by 3 (the default number of replicas)

Row 7: Import speed

Panels in seventh row

Panel Series Description
Delivery duration Range delivery Time taken to upload a range of KV pairs to the TiKV cluster
Delivery duration SST delivery Time taken to upload an SST file to the TiKV cluster
SST process duration Split SST Time taken to split the stream of KV pairs into SST files
SST process duration SST upload Time taken to upload an SST file
SST process duration SST ingest Time taken to ingest an uploaded SST file
SST process duration SST size File size of an SST file

Monitoring metrics

This section explains the monitoring metrics of tidb-lightning.

Metrics provided by tidb-lightning are listed under the namespace lightning_*.

  • lightning_importer_engine (Counter)

    Counts open and closed engine files. Labels:

    • type:
      • open
      • closed

  • lightning_idle_workers (Gauge)

    Counts idle workers. Labels:

    • name:
      • table: the remainder of table-concurrency, normally 0 until the end of the process
      • index: the remainder of index-concurrency, normally 0 until the end of the process
      • region: the remainder of region-concurrency, normally 0 until the end of the process
      • io: the remainder of io-concurrency, normally close to configured value (default 5), and close to 0 means the disk is too slow
      • closed-engine: number of engines which have been closed but not yet cleaned up, normally close to index + table-concurrency (default 8). A value close to 0 means TiDB Lightning is faster than TiKV Importer, which might cause TiDB Lightning to stall

  • lightning_kv_encoder (Counter)

    Counts open and closed KV encoders. KV encoders are in-memory TiDB instances that convert SQL INSERT statements into KV pairs. The net values need to be bounded in a healthy situation. Labels:

    • type:
      • open
      • closed

  • lightning_tables (Counter)

    Counts processed tables and their statuses. Labels:

    • state: the status of the table, indicating which phase should be completed
      • pending: not yet processed
      • written: all data encoded and sent
      • closed: all corresponding engine files closed
      • imported: all engine files have been imported into the target cluster
      • altered_auto_inc: AUTO_INCREMENT ID altered
      • checksum: checksum performed
      • analyzed: statistics analysis performed
      • completed: the table has been fully imported and verified
    • result: the result of the current phase
      • success: the phase completed successfully
      • failure: the phase failed (did not complete)

  • lightning_engines (Counter)

    Counts number of engine files processed and their status. Labels:

    • state: the status of the engine, indicating which phase should be completed
      • pending: not yet processed
      • written: all data encoded and sent
      • closed: engine file closed
      • imported: the engine file has been imported into the target cluster
      • completed: the engine has been fully imported
    • result: the result of the current phase
      • success: the phase completed successfully
      • failure: the phase failed (did not complete)

  • lightning_chunks (Counter)

    Counts number of chunks processed and their status. Labels:

    • state: a chunk's status, indicating which phase the chunk is in
      • estimated: (not a state) this value gives total number of chunks in current task
      • pending: loaded but not yet processed
      • running: data are being encoded and sent
      • finished: the entire chunk has been processed
      • failed: errors happened during processing

  • lightning_import_seconds (Histogram)

    Bucketed histogram for the time needed to import a table.

  • lightning_row_read_bytes (Histogram)

    Bucketed histogram for the size of a single SQL row.

  • lightning_row_encode_seconds (Histogram)

    Bucketed histogram for the time needed to encode a single SQL row into KV pairs.

  • lightning_row_kv_deliver_seconds (Histogram)

    Bucketed histogram for the time needed to deliver a set of KV pairs corresponding to one single SQL row.

  • lightning_block_deliver_seconds (Histogram)

    Bucketed histogram for the time needed to deliver a block of KV pairs to Importer.

  • lightning_block_deliver_bytes (Histogram)

    Bucketed histogram for the uncompressed size of a block of KV pairs delivered to Importer.

  • lightning_chunk_parser_read_block_seconds (Histogram)

    Bucketed histogram for the time needed by the data file parser to read a block.

  • lightning_checksum_seconds (Histogram)

    Bucketed histogram for the time needed to compute the checksum of a table.

  • lightning_apply_worker_seconds (Histogram)

    Bucketed histogram for the time needed to acquire an idle worker (see also the lightning_idle_workers gauge). Labels:

    • name:
      • table
      • index
      • region
      • io
      • closed-engine