https://github.com/gfngfn/a_strange_behavior_of_logger_formatter
See: https://github.com/erlang/otp/pull/6036
https://github.com/gfngfn/a_strange_behavior_of_logger_formatter
Last synced: 7 months ago
JSON representation
See: https://github.com/erlang/otp/pull/6036
- Host: GitHub
- URL: https://github.com/gfngfn/a_strange_behavior_of_logger_formatter
- Owner: gfngfn
- License: apache-2.0
- Created: 2022-05-31T00:59:50.000Z (over 3 years ago)
- Default Branch: master
- Last Pushed: 2022-05-31T02:14:42.000Z (over 3 years ago)
- Last Synced: 2025-01-16T00:00:07.182Z (9 months ago)
- Language: Erlang
- Homepage:
- Size: 6.84 KB
- Stars: 1
- Watchers: 2
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
This small application exemplifies a somewhat strange behavior of `logger_formatter`. It just counts up a number and emits logs every second.
The application has the following configuration for `config/sys.config`:
```erlang
[
{kernel, [
{logger_level, debug},
{logger, [
{handler, default, logger_std_h, #{
formatter =>
{logger_formatter, #{
template =>
%% The following does NOT work as intended:
[
{message_only,
["*", msg, "\n"],
[time, " [", level, "] ", file, ":", line, " ", pid, " ", msg, "\n"]
}
]
%% while the following does work:
%[
% {message_only,
% ["*"],
% [time, " [", level, "] ", file, ":", line, " ", pid, " "]
% },
% msg, "\n"
%]
}}
}}
]}
]}
].
```
As commented above, using the former list for the logger template does NOT work as intended, while the latter one does.
You can compile and run this application by:
```console
$ rebar3 shell
```
and can see how logs are emitted. Using the former one, logs look like:
```console
*
2022-05-31T09:58:33.889089+09:00 [info] : <0.142.0>
*
2022-05-31T09:58:35.890979+09:00 [info] : <0.142.0>
*
2022-05-31T09:58:37.892774+09:00 [info] : <0.142.0>
*
2022-05-31T09:58:39.894887+09:00 [info] : <0.142.0>
```
that is, `msg` is substituted with empty strings.
On the other hand, the latter template produces logs that look like:
```console
*count: 1
2022-05-31T10:00:48.543986+09:00 [info] : <0.142.0> count: 2
*count: 3
2022-05-31T10:00:50.545941+09:00 [info] : <0.142.0> count: 4
*count: 5
2022-05-31T10:00:52.547992+09:00 [info] : <0.142.0> count: 6
*count: 7
```
which reflects the intention correctly.
This behavior reproduces under the following environment:
```
$ erl
Erlang/OTP 24 [erts-12.0.1] [source] [64-bit] [smp:4:4] [ds:4:4:10] [async-threads:1] [jit] [dtrace]
Eshell V12.0.1 (abort with ^G)
1> q().
ok
2>
$ rebar3 version
rebar 3.16.1 on Erlang/OTP 24 Erts 12.0.1
```