Logging could impact application speed very much, especially during import or export.
You can setup the logging level from the config file or in any POST JSON request by attaching a parameter to a JSON object In t5memory there are 2 systems of logs - one from glog library and could be set in launch as commandline parameter and one is internal to filter out logs based on their level, can be set with every request that have json body with additional ["loggingThreshold": 0] parameter or at startup with flag.
[loggingThreshold:"2"]
Like here
POST http://localhost:4040/t5memory/example_tm/
{
sourceLang: “en”, // the source language is required for a new TM
name: „TM Name“,
loggingThreshold:"2"
}
This would set the logging level to INFO just before the main work of creating mem endpoint starts. DEVELOP could be used in really low level debugging, but most of the time DEBUG log is more useful, since DEVELOP would log a lot of logs. Transaction logs have the highest level of severity but it's severity is also changes with -v parameter, so with --v=2 it would be the highest log level(this log is not used often, it's only to track something like end or start of request) but with default --v=0 it's severity is belowe WARNING
Or in t5memory.conf file in line (config file is obsolete now)
logLevel=0
Would set the log level to DEVELOP, this would be applied only after restarting of service
gLog part - it have it's own configuration with command line flags. you can see all possible flags for t5memory with ./t5memory --help command.
main parameter here is --v and you can set it to 2 or 0(default).
By default it set to 0, in that case all not-errors would be avoided in logs, except startup.
idea of --v=1 was to have logBuffer to keep log in some stream and in case of error show previous logs for that request, but it seems not so usefull, so it was not fixed and it's not working properly
--v=2 is basicaly disables that buffering, so
In case of error or fatalError, log would be written with info about what request caused that log to happen(but that info would be truncated to 3000 symbols, this is important for importTMX), but if there are second error with the same request, new logs would not have that requests info
Some parameters combinations:
Default - --t5loglevel=2(T5INFO), --v=0, in this case you could see only init messages and errors only, with info about requests that caused error to happen
Change only --v=2 - t5loglevel would be set by default to 2(T5INFO), so you could see T5INFO, T5WARNING, T5ERROR, T5FATAL, T5TRANSACTION messages
Debug production --t5loglevel=1(T5DEBUG), --v=2 - should be enough to have some info about issues, a lot of logs, but not as much as with Develop
Develop --t5loglevel=0(T5DEVELOP), --v=2 - all possible logs, includes entering to some functions, some step-by-step mechanisms logs(like how t5memory is parsing and hashing strings) etc. Useful only when you can reproduce issue so you don't get lost in logs from just normal behaviour or when it's crashing etc.
It's possible to change t5loglevel with some requests, so for example for some specific update request, you can set it to some lower log level and then set it back. It would affect other threads, but since in logs you have info about thread, it could be useful tool.
Seems like --v parameter it's not quite useful, maybe should be refactored, since with --v=0 you wouldn't get any messages with severity lower than T5ERROR, except init process.
But gLog library could be connected to some other libs in proxygen package
Here are all glog flags:
Flags from src/logging.cc:
-alsologtoemail (log messages go to these email addresses in addition to
logfiles) type: string default: ""
-alsologtostderr (log messages go to stderr in addition to logfiles)
type: bool default: false
-colorlogtostderr (color messages logged to stderr (if supported by
terminal)) type: bool default: false
-drop_log_memory (Drop in-memory buffers of log contents. Logs can grow
very quickly and they are rarely read before they need to be evicted from
memory. Instead, drop them from memory as soon as they are flushed to
disk.) type: bool default: true
-log_backtrace_at (Emit a backtrace when logging at file:linenum.)
type: string default: ""
-log_dir (If specified, logfiles are written into this directory instead of
the default logging directory.) type: string default: ""
currently: "/root/.t5memory/LOG/"
-log_link (Put additional links to the log files in this directory)
type: string default: ""
-log_prefix (Prepend the log prefix to the start of each log line)
type: bool default: true
-logbuflevel (Buffer log messages logged at this level or lower (-1 means
don't buffer; 0 means buffer INFO only; ...)) type: int32 default: 0
-logbufsecs (Buffer log messages for at most this many seconds) type: int32
default: 30
-logemaillevel (Email log messages logged at this level or higher (0 means
email all; 3 means email FATAL only; ...)) type: int32 default: 999
-logfile_mode (Log file mode/permissions.) type: int32 default: 436
-logmailer (Mailer used to send logging email) type: string
default: "/bin/mail"
-logtostderr (log messages go to stderr instead of logfiles) type: bool
default: false
-max_log_size (approx. maximum log file size (in MB). A value of 0 will be
silently overridden to 1.) type: int32 default: 1800
-minloglevel (Messages logged at a lower level than this don't actually get
logged anywhere) type: int32 default: 0
-stderrthreshold (log messages at or above this level are copied to stderr
in addition to logfiles. This flag obsoletes --alsologtostderr.)
type: int32 default: 2
-stop_logging_if_full_disk (Stop attempting to log to disk if the disk is
full.) type: bool default: false