Add back gzip to default features update docs (#144)

* Add back gzip to default features update docs

Cargo.toml

@@ -10,7 +10,7 @@ keywords = ["log", "logger", "logging", "log4"]
 edition = '2018'
 
 [features]
-default = ["all_components", "file", "yaml_format"]
+default = ["all_components", "file", "yaml_format", "gzip"]
 
 file = ["humantime", "serde", "serde_derive", "serde-value", "typemap", "log/serde"]
 yaml_format = ["serde_yaml"]

README.md

@@ -9,7 +9,22 @@
 log4rs is a highly configurable logging framework modeled after Java's Logback
 and log4j libraries.
 
-[Documentation](https://docs.rs/log4rs)
+### Warning
+
+If you are using the file rotation in your configuration there is a known substantial performance issue so listen up!
+By default the `gzip` feature is enabled and when rolling files it will zip log archives automatically. This is a problem
+when the log archives are large as the zip happens in the main thread and will halt the process while the zip is completed.
+Be advised that the `gzip` feature will be removed from default features as of `1.0`.
+
+The methods to mitigate this are as follows.
+
+1. Use the `background_rotation` feature which spawns an os thread to do the compression.
+1. Disable the `gzip` feature with `--no-default-features`.
+1. Ensure the archives are small enough that the compression time is acceptable.
+
+For more information see the PR that added (`background_rotation`)[https://github.com/estk/log4rs/pull/117].
+
+## Quick Start
 
 log4rs.yaml:
 ```yaml

benches/rotation.rs

@@ -36,6 +36,7 @@ fn bench_find_anomalies() {
         let dur = now.elapsed();
 
         if i > 100
+            && dur.as_millis() > 10
             && dur.as_micros() as u64 > (online.mean() + (online.stddev() * 50_f64)).round() as u64
         {
             anomalies.push(dur);