首页 \ 问答 \ python是并发编程的一个重要选项(Is python a serious option for concurrent programming)

python是并发编程的一个重要选项(Is python a serious option for concurrent programming)

只是考虑开始学习python,但在投入更多时间之前,我有一个担心。 让我把这句话作为一种声明加以说明,然后再考虑其他人对此发表评论,因为声明中的假设可能是无效的:

我已阅读关于GIL和共识似乎是如果你需要Python中的并发解决方案,你最好的选择是分叉一个新的过程,以避免GIL。

我担心的是,如果我遇到了问题,我想在N个处理器之间拆分成N * 2个部分(假设例如我有一个服务器运行带有8个内核的* nix o / s),则会产生上下文切换处罚在进程之间而不是在线程之间,这会更加昂贵,这会限制性能。

我问这是因为其他语言在那里声称在这样的场景中表现突出,我想知道Python是否适合这个舞台。


just considering starting to learning python but I have one concern before I invest more time. Let me phrase this as a statement followed by a concern for others to comment on as perhaps the assumptions in the statement are invalid:

I have read about GIL and the consensus seems to be if you require concurrent solutions in python your best bet is to fork a new process to avoid GIL.

My concern is that if I have a problem I'd like to split into N*2 pieces across N processors (assume for example I have a single server running a *nix o/s with say 8 cores) I will incur context switching penalties between processes rather than between threads, which is more costly, which will limit performance.

I ask this because other languages are out there that claim to excel in such a scenario and I wonder is python appropriate for this arena.


原文:https://stackoverflow.com/questions/2150144
更新时间:2023-08-15 19:08

最满意答案

你可以通过使用数组作为堆栈来解决这个问题。 下面的代码的评论有一个正确的解释。

function parseTree(string) {
  // split string into an array
  // reduce the array into a proper tree where the 
  // first and last item will be the entire tree, hence,
  // the access of the first index from the last part
  // of this expression
  return string.split(/(}|{|\-)/)
    .reduce(parseTreeReducer, [])[0];
}

function parseTreeReducer(array, ch, index, original) {
  // always track the index of the open bracket 
  // from the array stack
  let indexBracket = array.lastIndexOf('{');

  if(ch === '{') { // is it an open bracket?
    // store it in the array stack!
    array.push(ch); 
  } else if(ch === '}') { // is it a close bracket?
    // remove the last open bracket
    // this prepares the nodes after the open bracket index
    // to be the children of the next node
    array.splice(indexBracket, 1); 
  } else if(ch !== '-' && ch) { // make sure to ignore '-' key

    // push the node in the array stack
    array.push({ 
      name: ch, // name
      // ensure that we only get the nodes that are after the 
      // last open bracket from the array stack and remove them.
      // These removed nodes will be assigned as children for
      // this current node
      children: array.splice(
        // make sure we don't delete the open bracket
        indexBracket + 1, 
        // only remove items beyond the open bracket index
        array.length - indexBracket - 1 
      ).reverse() // reverse to represent the expected output (optional!)
    });

  }
  // return the array stack
  return array;
}

function parseTree(string) {
  // split string into an array
  // reduce the array into a proper tree where the 
  // first and last item will be the entire tree, hence,
  // the access of the first index from the last part
  // of this expression
  return string.split(/(}|{|\-)/)
    .reduce(parseTreeReducer, [])[0];
}

function parseTreeReducer(array, ch, index, original) {
  // always track the index of the open bracket 
  // from the array stack
  let indexBracket = array.lastIndexOf('{');

  if(ch === '{') { // is it an open bracket?
    // store it in the array stack!
    array.push(ch); 
  } else if(ch === '}') { // is it a close bracket?
    // remove the last open bracket
    // this prepares the nodes after the open bracket index
    // to be the children of the next node
    array.splice(indexBracket, 1); 
  } else if(ch !== '-' && ch) { // make sure to ignore '-' key
  
    // push the node in the array stack
    array.push({ 
      name: ch, // name
      // ensure that we only get the nodes that are after the 
      // last open bracket from the array stack and remove them.
      // These removed nodes will be assigned as children for
      // this current node
      children: array.splice(
        // make sure we don't delete the open bracket
        indexBracket + 1, 
        // only remove items beyond the open bracket index
        array.length - indexBracket - 1 
      ).reverse() // reverse to represent the expected output (optional!)
    });

  }
  // return the array stack
  return array;
}

/* THE CODE BELOW IS ONLY FOR DEMO USAGE */

var input = document.querySelector('input');
var output = document.querySelector('pre');

setOutput();
input.addEventListener('keyup', setOutput);

function setOutput() {
  output.innerHTML = JSON.stringify(parseTree(input.value), 0, 4);
}
.as-console-wrapper{min-height:100%;top:0}
input{width: 100%}
pre{background-color: #ccc; padding: 1em}
<input type="text" 
  autofocus 
  value="{{Axe-Barathrum-Clockwork}{Abaddon-Clinkz-Bane Elemental}Dragon Knight-Bristleback}{Ezalor}Furion" />

<br>

<pre></pre>


You can solve this by using arrays as stacks. There's a proper explanation from the comments of the code below.

function parseTree(string) {
  // split string into an array
  // reduce the array into a proper tree where the 
  // first and last item will be the entire tree, hence,
  // the access of the first index from the last part
  // of this expression
  return string.split(/(}|{|\-)/)
    .reduce(parseTreeReducer, [])[0];
}

function parseTreeReducer(array, ch, index, original) {
  // always track the index of the open bracket 
  // from the array stack
  let indexBracket = array.lastIndexOf('{');

  if(ch === '{') { // is it an open bracket?
    // store it in the array stack!
    array.push(ch); 
  } else if(ch === '}') { // is it a close bracket?
    // remove the last open bracket
    // this prepares the nodes after the open bracket index
    // to be the children of the next node
    array.splice(indexBracket, 1); 
  } else if(ch !== '-' && ch) { // make sure to ignore '-' key

    // push the node in the array stack
    array.push({ 
      name: ch, // name
      // ensure that we only get the nodes that are after the 
      // last open bracket from the array stack and remove them.
      // These removed nodes will be assigned as children for
      // this current node
      children: array.splice(
        // make sure we don't delete the open bracket
        indexBracket + 1, 
        // only remove items beyond the open bracket index
        array.length - indexBracket - 1 
      ).reverse() // reverse to represent the expected output (optional!)
    });

  }
  // return the array stack
  return array;
}

function parseTree(string) {
  // split string into an array
  // reduce the array into a proper tree where the 
  // first and last item will be the entire tree, hence,
  // the access of the first index from the last part
  // of this expression
  return string.split(/(}|{|\-)/)
    .reduce(parseTreeReducer, [])[0];
}

function parseTreeReducer(array, ch, index, original) {
  // always track the index of the open bracket 
  // from the array stack
  let indexBracket = array.lastIndexOf('{');

  if(ch === '{') { // is it an open bracket?
    // store it in the array stack!
    array.push(ch); 
  } else if(ch === '}') { // is it a close bracket?
    // remove the last open bracket
    // this prepares the nodes after the open bracket index
    // to be the children of the next node
    array.splice(indexBracket, 1); 
  } else if(ch !== '-' && ch) { // make sure to ignore '-' key
  
    // push the node in the array stack
    array.push({ 
      name: ch, // name
      // ensure that we only get the nodes that are after the 
      // last open bracket from the array stack and remove them.
      // These removed nodes will be assigned as children for
      // this current node
      children: array.splice(
        // make sure we don't delete the open bracket
        indexBracket + 1, 
        // only remove items beyond the open bracket index
        array.length - indexBracket - 1 
      ).reverse() // reverse to represent the expected output (optional!)
    });

  }
  // return the array stack
  return array;
}

/* THE CODE BELOW IS ONLY FOR DEMO USAGE */

var input = document.querySelector('input');
var output = document.querySelector('pre');

setOutput();
input.addEventListener('keyup', setOutput);

function setOutput() {
  output.innerHTML = JSON.stringify(parseTree(input.value), 0, 4);
}
.as-console-wrapper{min-height:100%;top:0}
input{width: 100%}
pre{background-color: #ccc; padding: 1em}
<input type="text" 
  autofocus 
  value="{{Axe-Barathrum-Clockwork}{Abaddon-Clinkz-Bane Elemental}Dragon Knight-Bristleback}{Ezalor}Furion" />

<br>

<pre></pre>

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