# resharper-heapview

**Repository Path**: ofri/resharper-heapview

## Basic Information

- **Project Name**: resharper-heapview
- **Description**: https://github.com/controlflow/resharper-heapview.git
- **Primary Language**: Unknown
- **License**: MIT
- **Default Branch**: master
- **Homepage**: None
- **GVP Project**: No

## Statistics

- **Stars**: 0
- **Forks**: 0
- **Created**: 2020-12-24
- **Last Updated**: 2020-12-24

## Categories & Tags

**Categories**: Uncategorized

**Tags**: None

## README

HeapAllocationViewer for Rider and ReSharper
--------------------------------------------

[![Rider](https://img.shields.io/jetbrains/plugin/v/9223-heap-allocations-viewer.svg?label=rider%20&colorB=0A7BBB&style=flat-square&logo=%20data%3Aimage%2Fpng%3Bbase64%2CiVBORw0KGgoAAAANSUhEUgAAADAAAAAsCAYAAAAjFjtnAAAAAXNSR0IArs4c6QAAAARnQU1BAACxjwv8YQUAAAAJcEhZcwAADsMAAA7DAcdvqGQAAAAZdEVYdFNvZnR3YXJlAHBhaW50Lm5ldCA0LjAuMjHxIGmVAAAEEklEQVRoQ%2B2ZS0hUURjHLSoKominVIta1aLaFYhBES1t1bLFRCAREbQKaiHpqgeEpjDjRhIFHWwzIyo6oWXqwmfkW0evr9TxNT7GcZxX%2FzPzzZk53jsyc%2B91I%2FcHB4a5%2F%2B%2B79z%2Fn3O98RzOOBKFQ6BeGlOrw%2B%2F2S0%2Bn83dXV9a6srOwSpUlKfX19yvnn5%2BelwcFBW09Pz8uamporlOJgEOgMq2R7ezuAm33Cx%2BOUTgYMqMq%2Ft7cX7O3t7QbXKJUyWgzEWFhYaMONTlJKAbUGYvh8vjBymy0Wi2J%2BXQwwxsbGvlFKAa0GGHjG8Nra2nd8lM%2B0kgGPx9OK76sSx9LSkgNrfyMQCOySTAAxodLS0uuUlqNkAPnG9%2BdfWVlxLC8vs%2FxBkskYHx%2B3Udo4CJbdoKqqKpcuy8DLmzU3N%2FeTpAJTU1MfSMZRMoBCYKHLMhwOx12YacBzkVpkeHjYRNIo6RpgsPXodrtdJOdgvdpJwknXQIyRkZE3mA2KiIP7LqJCnSGZOgMM3MBOcg5y6WaAsb6%2B%2Fp5CBDo7O5%2BSRL0BTOWhG2hpaTnt9Xr%2FURhndna2lSTqDWxtbUkk50xOTupqgDE9PV1AYZzV1VVXXl5etKyma6C8vDwTJa2GpALY1J6QjKPVAGY6l8I4mJVwR0dH9D1QMtDW1ubCjaXE0dDQIA0MDEj45f0kE0DlmMeUn4gkTUCrgYqKCpkBxszMTHID6YJq4cVU50QS7kOrAZvNJjOAZ9bPAHoWT3Nz84tIMgW0GsC%2B84rCOFjCYV5K1RpgPQo2tKbi4uLbkURJ0GoALUo3hXHQRP7BpWMRgZIBrGcPpmgjNjY3N2XtA16knb6%2BvouRJAegxUB1dXVuMCjvLCYmJspIomwA3wlVqL29PXt3d1e2t6MeD%2BTn58te3ETUGkDByMTyHKMQDmL9drv9FslSM8DAzvuRLgtgjX4miSJqDOCdugfNKMkFJElqIlmUVA0w0PdPkISDmQk3NjZmk0SGkgF0tq2VlZWm2ECpNFmtVtPi4uJzLN8fuD8pRdBa%2BIaGhrIodZR0DKCk5WBafSTj4IEmMeWnSCagZEANmBEPVsEDShsnHQOM%2Fv7%2BLyQTQPKvJBHQwwCqjhet%2Bn1KKZKuAfQg51GH%2F5KUw5bS6OjoHZJxtBjAr876q14ssxuUTk66Bhg4dNzECYzUcbAv7KCPukCyCGoMIPcaGjYrK6NIEa33ycBb%2FRhtgClx4EEu0%2BWkoPo83B%2FHBo59QqzZbH4LE7UHjbq6ulpsjM9QJEwFBQWPlHoqAwMDAwMDAwODo0hJScnZoqKic3oOHPST%2Fs9Md1wulxMjrNfAuZYdbK5S%2BsNH6UCjBfZ3HJgwDKQMDLzGKNRrwECh2%2B0WjpUGimRk%2FAdgThdOY4UJ9QAAAABJRU5ErkJggg%3D%3D)](https://plugins.jetbrains.com/plugin/9223-heap-allocations-viewer)
[![ReSharper](https://img.shields.io/resharper/v/ReSharperPlugin.HeapAllocationViewer.svg?label=resharper%20&colorB=0A7BBB&style=flat-square&logo=%20data%3Aimage%2Fpng%3Bbase64%2CiVBORw0KGgoAAAANSUhEUgAAADIAAAAxCAYAAACYq%2FofAAAAAXNSR0IArs4c6QAAAARnQU1BAACxjwv8YQUAAAAJcEhZcwAADsMAAA7DAcdvqGQAAAAZdEVYdFNvZnR3YXJlAHBhaW50Lm5ldCA0LjAuMjHxIGmVAAAE%2BElEQVRoQ%2B2Ya0hkZRzG3d1oWehLLQS2QRC1tEWflhLqU0QgsbAb6ZesiL5KXxKE3GBa86uE0IdWiTJq8BLGMiqapnjDYfAy3jCv6XgfZC7explxnJ73zDPvnOM7M%2BtlslrOD%2F7InOc5%2F%2Ff8z3mvZplkgJKSkuzS0tIb8bBYLC9RMoDr1%2FW%2B4uLiG5RUDg8PFxCek4Tf7%2Fe4XK7W0dHRosbGxieZ6tg4nU7%2F3t5eNB67u7tBSpK8vLwr29vbXr1veno6Ci7QYgSCT6inJRQK7UxNTd3F23ucKR%2FGBbyMAG%2FXWFpaClCT2Gy2F4PBIB0x0FYbZRXoZyokzszMTFdtbe0Vpk1JTU3NawcHB7wrBn7XU5a0tLS8Q1kyNDRko6wCPSOFCCYnJ2uYNiXLy8tv0y4ZHx%2F%2FnrIEL6aIsmRlZeUzyirQM1YI3mxodXX1OaZOCvr517RLPB7PR5QlGH9WyhIM%2BDzKKtCVQtCHf8Cfi0ejsLDwGfTdj2dnZ23hcPgQ1xRQSAVTayDXbYQ1Hmtra7u0SlDc4djYWEQfW1tbVBNMTExoWldX1wzTJ4CetBDKKbHb7Rb4eEeCjY2NOVo04PmCUsbAyzC0oYHrpyokNzf3Mvp7mLdIcO%2F%2FqxAButdPvEVyHoWg3cwWgi8yy1skSQr5HOEXEYlEDOuHAIteAN3Rrw8Qoizx%2BXzbcd3tdjuZPoHwxKwJjlNIX1%2FfG3gwZZBgsI%2FSooAuoXyd9vb2IsoSDOp6yhp4nmggEHiBcnLgO1EhdXV1l3p7ewuwrdik3QC%2B0pe0KmBK7aFNQzzg8PDwNcoSfJE%2FaNHA9iRUWVn5LOXkwKcUsrm5GcEqGjwaIyMjwZ2dnaB4gGSguHB1dfV1pjaQn59%2Fyev1TtCqgd%2FRqqqqp2iRrK%2Bv0xFjf39%2FlVJq4FMKOQ3oZtH%2B%2Fv57TKsgti94QXTHwKCdpCzBzvgaZQm%2Bsp1yauA7cyFic4civmXKpGBVfpV2CRZCB2XJ4OBgLmUJvtx3lFMD35kKwf5nrbOz8w5SKdtrdMGfEZsi8Pa3eYsE1%2Ffiui6UJV3MdnF9YWHhPtMbge%2FUhSwuLkYKCgqymUoBDT%2BgNWOgkF%2BY3gg0pRDMEn%2FOzc3d1we6zwZlA5gqq5lK4V8vBA%2BgTL%2BYJt%2FD9QgtEnSZcFtb2y3aDPwnCxHMz88bFqo4WHVXm5ubL9MmQZ4yRAdW7yFaJVjgQkLTB44BDsoSjA%2B33oMZ7C7TG4H32IWUlZVlo9st0WYAx9UfaVMoLy9%2FCznpjIFV%2FnfKku7u7luUJVi7fqWcHniPXYgAjd1Bb6IzgVhHcFb5lDYD2La8S5sEC6zSBh76K8oSLMCfUE4PvCcqxGKxXMTgV05vAhyGvHj7ypYDW5NvaJFg2v6AsgRH3t8oSyoqKm5TTg%2B8JypE0NDQcBVvWVkXBCiylTYJthx1lCXYmrxJWYKd7V%2BUNfhflMcopwfGExciwEz1figUEud0Q4hrDofjQ9o0XC6XT%2B%2FBnixKSYJj9FVMGjt6Hwa2W%2BzRaEkPnvsmHjxHH7j2POW04Mu83tHRkXM0rFbrK7Ro9PT03NTr9fX1OZQk4v9ira2thjzY4r9M2cTExMTExMTExMTkEaSpqemB3W5fznTg2LrMJs6HgYEB5YSYKdjE%2BfDIFOJ0Ol1sN%2BOwifMB7T2Bc%2FrT%2F0SwCZOHk5X1N%2Fu%2FydjP06PFAAAAAElFTkSuQmCC)](https://resharper-plugins.jetbrains.com/packages/ReSharperPlugin.HeapAllocationViewer)

This plugin statically analyzes C# code to find all local object allocations happening.

It can be used to reduce number of heap allocations in hot paths of your C# program.

![Example](https://raw.githubusercontent.com/controlflow/resharper-heapview/master/Content/Example.png)

#### Features

* It can detect and visualize [all boxing cases](http://stackoverflow.com/questions/7995606/boxing-occurrence-in-c-sharp), including:
```c#
struct Boxing {
  void M(string a) {
    object obj = 42;                // implicit conversion Int32 ~> Object
    string path = a + '/' + obj;    // implicit conversion Char ~> Object
    int code = this.GetHashCode();  // non-overriden virtual method call on struct
    string caseA = E.A.ToString();  // the same, virtual call
    IComparable comparable = E.A;   // valuetype conversion to interface type
    Action<string> action = this.M; // delegate from value type method
    Type type = this.GetType();     // GetType() call is always virtual
  }

  enum E { A, B, C }
}
```
* It can visualize some hidden allocations happening in C#, including:
```c#
class HeapAllocations {
  List<int> _xs = new List<int>();  // explicit object creation expressions
  int[] _ys = {1, 2, 3};            // allocation via array initializer syntax

  void M(params string[] args) {
    string c = args[0] + "/";       // string concatenation
    M("abc", "def");                // parameters array allocation
    M();                            // the same, hidden 'new string[0]'
    var xs = Enumerable.Range(0,1); // iterator method call
    var ys = from x in xs
             let y = x + 1          // anonymous type creation for 'let'
             select x + y;
  }

  void N(List<string> xs) {
    foreach (var s in xs) F(s);     // no allocations, value type enumerator

    IEnumerable<string> ys = xs;
    foreach (var s in ys) F(s);     // IEnumerator allocation in foreach
  }
}
```
* It can detect delegate instances allocation, ignoring cached delegates:
```c#
class Delegates {
  static void M(string s) {
    Action<string> method = M;      // non-cached delegate from method group
    Action lambda = () => M("a");   // cached delegate from static lambda
    Action closure = () => M(s);    // non-cached lambda with closure 's'
  }

  void M<T>() {
    Action generic = () => { };     // non-cached, lambda in generic method
    Action closure = () => M<T>();  // non-cached, captures 'this' to closure
  }
}
```
* It can detect closure ("display classes") creation points:
```c#
class Closures {
  IEnumerable<string> StupidExample(string str) {
    // <= hidden closure class allocation happens here
    if (str == null)
      return Enumerable.Empty<string>();

    if (str.Length == 0) {
      return Enumerable.Empty<string>();
    } else {
      // <= second hidden closure allocation (nested closure)
      int value = str.Count(x => x == '_');

      return Enumerable
        .Range(0, str.Length)
        .Select(count => // delegate instance allocation
          str.Substring(Math.Max(value, count)));
    }
  }
}
```

#### Notes

* Please, avoid premature optimizations. Use this tool with care, only when it matters to reduce allocations count;
* You can change default colors of highlightings in Visual Studio settings: go *Tools* - *Settings* - *Fonts and colors*
  and check colors for items *"ReSharper HeapView Boxing"* and *"ReSharper HeapView Allocation"*;
* You can change highlighting severity or search for all issues in project/solution as usual - via Alt+Enter menu over highlighting;
* This plugin highly relies on Microsoft's implementation of C# compiler shipping with VS,
  it may produce false positives for other C# implementations like Mono C# compiler;
* Plugin's [changelog is here](Changelog.md).