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Move object allocation out of loop

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Right now BenchmarkCleaner allocates hundreds of strings on every request with an exception. This patch moves those strings to be generated at boot once and re-used.

## Bench Methods

I took a modified form of CodeTriage https://github.com/schneems/codetriage-ko1-test-app/blob/master/perf.rake and ran given rake tasks with and without the patch to BacktraceCleaner.

I made an endpoint results in exception

```
  def index
    raise “foo"
  end
```

The gem `memory_profiler` was used to capture objects allocated for a single request. Then `benchmark/ips` was used to test the speed of the patch.

You will see that we use less objects and the code becomes measurably faster with this patch.

## With patch:

Memory for one request:

```
Total allocated 7441
Total retained 37
```

Requests per second:


```
Calculating -------------------------------------
                 ips         4 i/100ms
-------------------------------------------------
                 ips       43.0 (±4.7%) i/s -        216 in   5.037733s
```


## Without patch:

Memory used for one request:


```
Total allocated 11599
Total retained 35 
```

Requests per second:

```
Calculating -------------------------------------
                 ips         3 i/100ms
-------------------------------------------------
                 ips       39.4 (±7.6%) i/s -        198 in   5.052783s
```

## Analysis

The patch is faster:

```
(43.0 - 39.4 ) / 39.4 * 100
# => 9 # % ~ speed bump
```

It also allocates less objects:

```
11599 - 7441
# => 4158
```

These strings are allocated on __EVERY SINGLE REQUEST__. This patch saves us 4158 objects __PER REQUEST__ with exception.

Faster errors == Faster applications
This commit is contained in:
Richard Schneeman 2014-09-27 11:03:18 +08:00
parent 3f39ac4ee8
commit dfbcfafd9a
1 changed files with 9 additions and 4 deletions
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13
railties/lib/rails/backtrace_cleaner.rb
View File

@ -4,12 +4,16 @@ module Rails
class BacktraceCleaner < ActiveSupport::BacktraceCleaner
APP_DIRS_PATTERN = /^\/?(app|config|lib|test)/
RENDER_TEMPLATE_PATTERN = /:in `_render_template_\w*'/
EMPTY_STRING = ''.freeze
SLASH = '/'.freeze
DOT_SLASH = './'.freeze
def initialize
super
add_filter { |line| line.sub("#{Rails.root}/", '') }
add_filter { |line| line.sub(RENDER_TEMPLATE_PATTERN, '') }
add_filter { |line| line.sub('./', '/') } # for tests
@root = "#{Rails.root}/".freeze
add_filter { |line| line.sub(@root, EMPTY_STRING) }
add_filter { |line| line.sub(RENDER_TEMPLATE_PATTERN, EMPTY_STRING) }
add_filter { |line| line.sub(DOT_SLASH, SLASH) } # for tests
add_gem_filters
add_silencer { |line| line !~ APP_DIRS_PATTERN }
@ -21,7 +25,8 @@ def add_gem_filters
return if gems_paths.empty?
gems_regexp = %r{(#{gems_paths.join('|')})/gems/([^/]+)-([\w.]+)/(.*)}
add_filter { |line| line.sub(gems_regexp, '\2 (\3) \4') }
gems_result = '\2 (\3) \4'.freeze
add_filter { |line| line.sub(gems_regexp, gems_result) }
end
end
end