高并发、海量数据处理尽可能少使用using也能提高效率

时间 2019-11-29

原文原文链接

请看下面两段：html

第一种方式：程序员

                MemoryStream stream = new MemoryStream();

　　　　　　　　　 string text = "aasasdfasdfad;sas;fkqeworpkqwefkasdjfasdjf";
                byte[] buff = System.Text.ASCIIEncoding.ASCII.GetBytes(text);
                stream.Write(buff, 0, buff.Length);
                stream.Flush();
                stream.Close();
                stream.Dispose();

第二种方式：并发

            string text = "aasasdfasdfad;sas;fkqeworpkqwefkasdjfasdjf";
            using (MemoryStream stream = new MemoryStream())
            {
                byte[] buff = System.Text.ASCIIEncoding.ASCII.GetBytes(text);
                stream.Write(buff, 0, buff.Length);
                stream.Flush();
                stream.Close();
            }

不单单是我，估计一个老鸟程序员，大都会选择方法二，虽然方法一和方法二实现相同的功能，可是方法二带着套比较保险，即使咱们失手，不会制造出垃圾来（这话听着怪怪的，能理解我在说什么就好）。以后，我在作一些消息处理机制的接收、处理、分发测试中，发现使用using关键字和不用using关键字，效率有着很大差别，不使用using关键字效率明显偏高，MQ队列占用明显偏小，这是为何呢？答案立刻揭晓。ide

如下是经过反汇编工具所得的中间语言(IL)高并发

.method private hidebysig static void  Main(string[] args) cil managed
{
  .entrypoint
  // 代码大小       65 (0x41)
  .maxstack  4
  .locals init ([0] string text,
           [1] class [mscorlib]System.IO.MemoryStream 'stream',
           [2] uint8[] buff)
  IL_0000:  nop
  IL_0001:  ldstr      "aasasdfasdfad;sas;fkqeworpkqwefkasdjfasdjf"
  IL_0006:  stloc.0
  IL_0007:  newobj     instance void [mscorlib]System.IO.MemoryStream::.ctor()
  IL_000c:  stloc.1
  IL_000d:  call       class [mscorlib]System.Text.Encoding [mscorlib]System.Text.Encoding::get_ASCII()
  IL_0012:  ldloc.0
  IL_0013:  callvirt   instance uint8[] [mscorlib]System.Text.Encoding::GetBytes(string)
  IL_0018:  stloc.2
  IL_0019:  ldloc.1
  IL_001a:  ldloc.2
  IL_001b:  ldc.i4.0
  IL_001c:  ldloc.2
  IL_001d:  ldlen
  IL_001e:  conv.i4
  IL_001f:  callvirt   instance void [mscorlib]System.IO.Stream::Write(uint8[],
                                                                       int32,
                                                                       int32)
  IL_0024:  nop
  IL_0025:  ldloc.1
  IL_0026:  callvirt   instance void [mscorlib]System.IO.Stream::Flush()
  IL_002b:  nop
  IL_002c:  ldloc.1
  IL_002d:  callvirt   instance void [mscorlib]System.IO.Stream::Close()
  IL_0032:  nop
  IL_0033:  ldloc.1
  IL_0034:  callvirt   instance void [mscorlib]System.IO.Stream::Dispose()
  IL_0039:  nop
  IL_0040:  ret
} // end of method Program::Main

以上是方法一，所得中间语言，看起来很是干净、流畅。下面看看方法二的：工具

.method private hidebysig static void  Main(string[] args) cil managed
{
  .entrypoint
  // 代码大小       79 (0x4f)
  .maxstack  4
  .locals init ([0] string text,
           [1] class [mscorlib]System.IO.MemoryStream 'stream',
           [2] uint8[] buff,
 [3] bool CS$4$0000)
  IL_0000:  nop
  IL_0001:  ldstr      "aasasdfasdfad;sas;fkqeworpkqwefkasdjfasdjf"
  IL_0006:  stloc.0
  IL_0007:  newobj     instance void [mscorlib]System.IO.MemoryStream::.ctor()
  IL_000c:  stloc.1 .try { IL_000d: nop
    IL_000e:  call       class [mscorlib]System.Text.Encoding [mscorlib]System.Text.Encoding::get_ASCII()
    IL_0013:  ldloc.0
    IL_0014:  callvirt   instance uint8[] [mscorlib]System.Text.Encoding::GetBytes(string)
    IL_0019:  stloc.2
    IL_001a:  ldloc.1
    IL_001b:  ldloc.2
    IL_001c:  ldc.i4.0
    IL_001d:  ldloc.2
    IL_001e:  ldlen
    IL_001f:  conv.i4
    IL_0020:  callvirt   instance void [mscorlib]System.IO.Stream::Write(uint8[],
                                                                         int32,
                                                                         int32)
    IL_0025:  nop
    IL_0026:  ldloc.1
    IL_0027:  callvirt   instance void [mscorlib]System.IO.Stream::Flush()
    IL_002c:  nop
    IL_002d:  ldloc.1
    IL_002e:  callvirt   instance void [mscorlib]System.IO.Stream::Close()
    IL_0033:  nop
    IL_0034: nop IL_0035: leave.s IL_0047
 } // end .try finally {
    IL_0037:  ldloc.1 IL_0038: ldnull IL_0039: ceq IL_003b: stloc.3 IL_003c: ldloc.3 IL_003d: brtrue.s IL_0046 IL_003f: ldloc.1
    IL_0040:  callvirt   instance void [mscorlib]System.IDisposable::Dispose()
    IL_0045: nop IL_0046: endfinally } // end handler
  IL_0047:  pop
  IL_0048:  ret
} // end of method Program::Main

　　第二段IL中间红色部分即为不一样测试

[3] bool  CS$4$0000)
IL_000d: nop　　              中止几个时钟周期
IL_000d: nop
IL_0035: leave.s  IL_0047    退出受保护的代码区域，无条件将控制转移到目标指令
IL_0038: ldnull              将空引用（O 类型）推送到计算堆栈上
IL_0039: ceq                 比较两个值。若是这两个值相等，则将整数值 1 (int32) 推送到计算堆栈上；不然，将 0 (int32) 推送到计算堆栈上
IL_003b: stloc.3             从计算堆栈的顶部弹出当前值并将其存储到索引 3 处的局部变量列表中
IL_003c: ldloc.3             将索引 3 处的局部变量加载到计算堆栈上
IL_003d: brtrue.s  IL_0046   若是 value 为 true、非空或非零，则将控制转移到目标指令
IL_003f: ldloc.1             将索引 1 处的局部变量加载到计算堆栈上
IL_0045: nop
IL_0046: endfinally          将控制从异常块的 fault 或 finally 子句转移回公共语言结构 (CLI) 异常处理程序

IL指令汇总优化

　　可是刚刚咱们也提到了，虽然方法一和方法二实现相同的功能，可是方法二带着套比较保险，即使咱们失手，不会制造出垃圾来。即便是你忘记使用.close()、.dispose()方法释放资源，using仍是会自动帮你处理好你遗忘的的坏事。ui

　　因此在通常不要求高效开发中，尽可能使用using，可是在处理高并发、海量数据等等状况下，尽可能不要让using出现。spa

提示：

　　try..catch有必定的代码优化能力，少许代码测试，try..catch可能更优