Change the default log config to reduce disk I/O and storage (#8040)

* Change default log config to buffer by default.

This batches up writes to the filesystem, which is more efficient for
disk I/O. This means that it can take some time for logs to get written
to disk. Note that ERROR logs (and above) immediately flush the buffer.

This only effects new installs, as we only write the log config if
started with `--generate-config` (in the same way we do for generating
signing keys).

* Default to keeping last 4 days of logs.

This hopefully reduces the amount of logs kept for new servers. Keeping
the last 1GB of logs is likely overkill for new servers, but equally may
not be enough for busy ones.

Instead, we keep the last four days worth of logs, enough so that admins
can investigate any problems that happened over e.g. a long weekend.
This commit is contained in:
Erik Johnston 2020-08-11 18:09:46 +01:00 committed by GitHub
parent 0cb169900e
commit db131b6b22
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3 changed files with 73 additions and 10 deletions

1
changelog.d/8040.misc Normal file
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@ -0,0 +1 @@
Change the default log config to reduce disk I/O and storage for new servers.

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@ -18,13 +18,29 @@ filters:
handlers: handlers:
file: file:
class: logging.handlers.RotatingFileHandler class: logging.handlers.TimedRotatingFileHandler
formatter: precise formatter: precise
filename: /var/log/matrix-synapse/homeserver.log filename: /var/log/matrix-synapse/homeserver.log
maxBytes: 104857600 when: midnight
backupCount: 10 backupCount: 3 # Does not include the current log file.
filters: [context]
encoding: utf8 encoding: utf8
# Default to buffering writes to log file for efficiency. This means that
# will be a delay for INFO/DEBUG logs to get written, but WARNING/ERROR
# logs will still be flushed immediately.
buffer:
class: logging.handlers.MemoryHandler
filters: [context]
target: file
# The capacity is the number of log lines that are buffered before
# being written to disk. Increasing this will lead to better
# performance, at the expensive of it taking longer for log lines to
# be written to disk.
capacity: 10
flushLevel: 30 # Flush for WARNING logs as well
# A handler that writes logs to stderr. Unused by default, but can be used
# instead of "buffer" and "file" in the logger handlers.
console: console:
class: logging.StreamHandler class: logging.StreamHandler
formatter: precise formatter: precise
@ -36,8 +52,23 @@ loggers:
# information such as access tokens. # information such as access tokens.
level: INFO level: INFO
twisted:
# We send the twisted logging directly to the file handler,
# to work around https://github.com/matrix-org/synapse/issues/3471
# when using "buffer" logger. Use "console" to log to stderr instead.
handlers: [file]
propagate: false
root: root:
level: INFO level: INFO
handlers: [file, console]
# Write logs to the `buffer` handler, which will buffer them together in memory,
# then write them to a file.
#
# Replace "buffer" with "console" to log to stderr instead. (Note that you'll
# also need to update the configuation for the `twisted` logger above, in
# this case.)
#
handlers: [buffer]
disable_existing_loggers: false disable_existing_loggers: false

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@ -62,13 +62,29 @@ filters:
handlers: handlers:
file: file:
class: logging.handlers.RotatingFileHandler class: logging.handlers.TimedRotatingFileHandler
formatter: precise formatter: precise
filename: ${log_file} filename: ${log_file}
maxBytes: 104857600 when: midnight
backupCount: 10 backupCount: 3 # Does not include the current log file.
filters: [context]
encoding: utf8 encoding: utf8
# Default to buffering writes to log file for efficiency. This means that
# will be a delay for INFO/DEBUG logs to get written, but WARNING/ERROR
# logs will still be flushed immediately.
buffer:
class: logging.handlers.MemoryHandler
filters: [context]
target: file
# The capacity is the number of log lines that are buffered before
# being written to disk. Increasing this will lead to better
# performance, at the expensive of it taking longer for log lines to
# be written to disk.
capacity: 10
flushLevel: 30 # Flush for WARNING logs as well
# A handler that writes logs to stderr. Unused by default, but can be used
# instead of "buffer" and "file" in the logger handlers.
console: console:
class: logging.StreamHandler class: logging.StreamHandler
formatter: precise formatter: precise
@ -80,9 +96,24 @@ loggers:
# information such as access tokens. # information such as access tokens.
level: INFO level: INFO
twisted:
# We send the twisted logging directly to the file handler,
# to work around https://github.com/matrix-org/synapse/issues/3471
# when using "buffer" logger. Use "console" to log to stderr instead.
handlers: [file]
propagate: false
root: root:
level: INFO level: INFO
handlers: [file, console]
# Write logs to the `buffer` handler, which will buffer them together in memory,
# then write them to a file.
#
# Replace "buffer" with "console" to log to stderr instead. (Note that you'll
# also need to update the configuation for the `twisted` logger above, in
# this case.)
#
handlers: [buffer]
disable_existing_loggers: false disable_existing_loggers: false
""" """