mirror of
https://github.com/facebook/rocksdb.git
synced 2024-11-25 14:31:35 +00:00
e8a7001159
Summary: Pull Request resolved: https://github.com/facebook/rocksdb/pull/8744 Reviewed By: ltamasi Differential Revision: D30716145 Pulled By: akankshamahajan15 fbshipit-source-id: c2fcaf9ddcae85a86c0f10496acab28cd795ff12
97 lines
4.4 KiB
Markdown
97 lines
4.4 KiB
Markdown
# Rocksdb Tuning Advisor
|
|
|
|
## Motivation
|
|
|
|
The performance of Rocksdb is contingent on its tuning. However,
|
|
because of the complexity of its underlying technology and a large number of
|
|
configurable parameters, a good configuration is sometimes hard to obtain. The aim of
|
|
the python command-line tool, Rocksdb Advisor, is to automate the process of
|
|
suggesting improvements in the configuration based on advice from Rocksdb
|
|
experts.
|
|
|
|
## Overview
|
|
|
|
Experts share their wisdom as rules comprising of conditions and suggestions in the INI format (refer
|
|
[rules.ini](https://github.com/facebook/rocksdb/blob/main/tools/advisor/advisor/rules.ini)).
|
|
Users provide the Rocksdb configuration that they want to improve upon (as the
|
|
familiar Rocksdb OPTIONS file —
|
|
[example](https://github.com/facebook/rocksdb/blob/main/examples/rocksdb_option_file_example.ini))
|
|
and the path of the file which contains Rocksdb logs and statistics.
|
|
The [Advisor](https://github.com/facebook/rocksdb/blob/main/tools/advisor/advisor/rule_parser_example.py)
|
|
creates appropriate DataSource objects (for Rocksdb
|
|
[logs](https://github.com/facebook/rocksdb/blob/main/tools/advisor/advisor/db_log_parser.py),
|
|
[options](https://github.com/facebook/rocksdb/blob/main/tools/advisor/advisor/db_options_parser.py),
|
|
[statistics](https://github.com/facebook/rocksdb/blob/main/tools/advisor/advisor/db_stats_fetcher.py) etc.)
|
|
and provides them to the [Rules Engine](https://github.com/facebook/rocksdb/blob/main/tools/advisor/advisor/rule_parser.py).
|
|
The Rules uses rules from experts to parse data-sources and trigger appropriate rules.
|
|
The Advisor's output gives information about which rules were triggered,
|
|
why they were triggered and what each of them suggests. Each suggestion
|
|
provided by a triggered rule advises some action on a Rocksdb
|
|
configuration option, for example, increase CFOptions.write_buffer_size,
|
|
set bloom_bits to 2 etc.
|
|
|
|
## Usage
|
|
|
|
### Prerequisites
|
|
The tool needs the following to run:
|
|
* python3
|
|
|
|
### Running the tool
|
|
An example command to run the tool:
|
|
|
|
```shell
|
|
cd rocksdb/tools/advisor
|
|
python3 -m advisor.rule_parser_example --rules_spec=advisor/rules.ini --rocksdb_options=test/input_files/OPTIONS-000005 --log_files_path_prefix=test/input_files/LOG-0 --stats_dump_period_sec=20
|
|
```
|
|
|
|
### Command-line arguments
|
|
|
|
Most important amongst all the input that the Advisor needs, are the rules
|
|
spec and starting Rocksdb configuration. The configuration is provided as the
|
|
familiar Rocksdb Options file (refer [example](https://github.com/facebook/rocksdb/blob/main/examples/rocksdb_option_file_example.ini)).
|
|
The Rules spec is written in the INI format (more details in
|
|
[rules.ini](https://github.com/facebook/rocksdb/blob/main/tools/advisor/advisor/rules.ini)).
|
|
|
|
In brief, a Rule is made of conditions and is triggered when all its
|
|
constituent conditions are triggered. When triggered, a Rule suggests changes
|
|
(increase/decrease/set to a suggested value) to certain Rocksdb options that
|
|
aim to improve Rocksdb performance. Every Condition has a 'source' i.e.
|
|
the data source that would be checked for triggering that condition.
|
|
For example, a log Condition (with 'source=LOG') is triggered if a particular
|
|
'regex' is found in the Rocksdb LOG files. As of now the Rules Engine
|
|
supports 3 types of Conditions (and consequently data-sources):
|
|
LOG, OPTIONS, TIME_SERIES. The TIME_SERIES data can be sourced from the
|
|
Rocksdb [statistics](https://github.com/facebook/rocksdb/blob/main/include/rocksdb/statistics.h)
|
|
or [perf context](https://github.com/facebook/rocksdb/blob/main/include/rocksdb/perf_context.h).
|
|
|
|
For more information about the remaining command-line arguments, run:
|
|
|
|
```shell
|
|
cd rocksdb/tools/advisor
|
|
python3 -m advisor.rule_parser_example --help
|
|
```
|
|
|
|
### Sample output
|
|
|
|
Here, a Rocksdb log-based rule has been triggered:
|
|
|
|
```shell
|
|
Rule: stall-too-many-memtables
|
|
LogCondition: stall-too-many-memtables regex: Stopping writes because we have \d+ immutable memtables \(waiting for flush\), max_write_buffer_number is set to \d+
|
|
Suggestion: inc-bg-flush option : DBOptions.max_background_flushes action : increase suggested_values : ['2']
|
|
Suggestion: inc-write-buffer option : CFOptions.max_write_buffer_number action : increase
|
|
scope: col_fam:
|
|
{'default'}
|
|
```
|
|
|
|
## Running the tests
|
|
|
|
Tests for the code have been added to the
|
|
[test/](https://github.com/facebook/rocksdb/tree/main/tools/advisor/test)
|
|
directory. For example, to run the unit tests for db_log_parser.py:
|
|
|
|
```shell
|
|
cd rocksdb/tools/advisor
|
|
python3 -m unittest -v test.test_db_log_parser
|
|
```
|