In the early days of Windows, a floppy could be crashed when the formatting process was interrupted because of the floppy disk itself was still moving. So, if the &#39;multitasking operating system&#39; Windows really executes a different time consuming task, you had to throw away your floppy. So the funny thing is, that Microsoft called that mess a &#39;multitasking operation system&#39;.

I have a Symfony2 project. I updated my php to 5.5.7 today and since then, I am getting the 

    Warning: date_default_timezone_get(): It is not safe to rely on the system&#39;s timezone settings. You are *required* to use the date.timezone setting or the date_default_timezone_set() function. In case you used any of those methods and you are still getting this warning, you most likely misspelled the timezone identifier. We selected the timezone &#39;UTC&#39; for now, but please set date.timezone to select your timezone. in...

I setup the default timezone in my php.ini

    [Date]
    ; Defines the default timezone used by the date functions
    ; http://php.net/date.timezone
    date.timezone = &quot;Europe/Paris&quot;;

To be sure that this is the good php.ini, I was checking with 

    phpinfo();

And the path I ma getting there is the one I am modifying:

     /usr/local/php5.5.7/lib 

But in there, I see the 

    Default timezone 	UTC 
Which is strange.

any idea? Thank you.


Symfony2 and date_default_timezone_get() - It is not safe to rely on the system&#39;s timezone settings

I know how I can rename files and such, but I&#39;m having trouble with this.

I only need to rename `test-this` in a for loop.

    test-this.ext
    test-this.volume001+02.ext
    test-this.volume002+04.ext 
    test-this.volume003+08.ext 
    test-this.volume004+16.ext 
    test-this.volume005+32.ext 
    test-this.volume006+64.ext 
    test-this.volume007+78.ext 

Rename multiple files, but only rename part of the filename in Bash

I was reading up the difference between [Thread and Processes][1] and came across the comment left by users in the second answer which stated

&gt; As so long as you don&#39;t format a floppy at the same time.

It has 27 upvotes but no one has explained the reason behind it .

I would like to know what the commentor means when he said the above comment ??

Can someone suggest a more meaningful question name which reflects what the question is asking


  [1]: https://stackoverflow.com/questions/200469/what-is-the-difference-between-a-process-and-a-thread

Why was the comment that said &quot;Don&#39;t format a floppy at the same time&quot; funny when talking about threads and processes?

I was reading up the difference between <a href="https://stackoverflow.com/questions/200469/what-is-the-difference-between-a-process-and-a-thread" target="_blank" rel="noopener noreferrer">Thread and Processes</a> and came across the comment left by users in the second answer which stated
> As so long as you don't format a floppy at the same time.
It has 27 upvotes but no one has explained the reason behind it .
I would like to know what the commentor means when he said the above comment ??
Can someone suggest a more meaningful question name which reflects what the question is asking

I was just very confused by some code that I wrote. I was surprised to discover that:


    with concurrent.futures.ThreadPoolExecutor(max_workers=4) as executor:
        results = list(executor.map(f, iterable))

and 


    with concurrent.futures.ThreadPoolExecutor(max_workers=4) as executor:
        results = list(map(lambda x: executor.submit(f, x), iterable))

produce different results. The first one produces a list of whatever type `f` returns, the second produces a list of `concurrent.futures.Future` objects that then need to be evaluated with their `result()` method in order to get the value that `f` returned. 

My main concern is that this means that `executor.map` can&#39;t take advantage of `concurrent.futures.as_completed`, which seems like an extremely convenient way to evaluate the results of some long-running calls to a database that I&#39;m making as they become available. 

I&#39;m not at all clear on how `concurrent.futures.ThreadPoolExecutor` objects work -- naively, I would prefer the (somewhat more verbose):

    with concurrent.futures.ThreadPoolExecutor(max_workers=4) as executor:
        result_futures = list(map(lambda x: executor.submit(f, x), iterable))
        results = [f.result() for f in futures.as_completed(result_futures)]

over the more concise `executor.map` in order to take advantage of a possible gain in performance. Am I wrong to do so?

How does ThreadPoolExecutor().map differ from ThreadPoolExecutor().submit?

In a library using Monitor.PulseAll() for thread synchronization, I noticed that the latency from the time PulseAll(...) is called to the time a thread is woken up seems to follow a &quot;stepping stair&quot; distribution -- with extremely large steps.  The woken threads are doing almost no work; and almost immediately go back to waiting on the monitor.  For example, on a box with 12 cores with 24 threads waiting on a Monitor (2x Xeon5680/Gulftown; 6 physical cores per processor; HT Disabled), the latency between the Pulse and a Thread waking up is as such:

![Latency using Monitor.PulseAll(); 3rd party library][1]

The first 12 threads (note we have 12 cores) take between 30 and 60 microseconds to respond.  Then we start getting very large jumps; with the plateaus around 700, 1300, 1900, and 2600 microseconds.

I was able to successfully recreate this behavior independent of the 3rd party library using the code below.  What this code does is launch a large number of threads (change the numThreads parameter) which just Wait on a Monitor, read a timestamp, log it to a ConcurrentSet, then immediately go back to Waiting.  Once a second PulseAll() wakes up all the threads.  It does this 20 times, and reports the latencies for the 10th iteration to the Console.

    using System;
    using System.Collections.Generic;
    using System.Linq;
    using System.Text;
    using System.Threading;
    using System.Threading.Tasks;
    using System.Collections.Concurrent;
    using System.Diagnostics;

    namespace PulseAllTest
    {
        class Program
        {
            static long LastTimestamp;
            static long Iteration;
            static object SyncObj = new object();
            static Stopwatch s = new Stopwatch();
            static ConcurrentBag&lt;Tuple&lt;long, long&gt;&gt; IterationToTicks = new ConcurrentBag&lt;Tuple&lt;long, long&gt;&gt;();

            static void Main(string[] args)
            {
                long numThreads = 32;

                for (int i = 0; i &lt; numThreads; ++i)
                {
                    Task.Factory.StartNew(ReadLastTimestampAndPublish, TaskCreationOptions.LongRunning);
                }
            
                s.Start();
                for (int i = 0; i &lt; 20; ++i)
                {
                    lock (SyncObj)
                    {
                        ++Iteration;
                        LastTimestamp = s.Elapsed.Ticks;
                        Monitor.PulseAll(SyncObj);
                    }
                    Thread.Sleep(TimeSpan.FromSeconds(1));
                }

                Console.WriteLine(String.Join(&quot;\n&quot;,
                    from n in IterationToTicks where n.Item1 == 10 orderby n.Item2 
                        select ((decimal)n.Item2)/TimeSpan.TicksPerMillisecond));
                Console.Read();
            }

            static void ReadLastTimestampAndPublish()
            {
                while(true)
                {
                    lock(SyncObj)
                    {
                        Monitor.Wait(SyncObj);
                    }
                    IterationToTicks.Add(Tuple.Create(Iteration, s.Elapsed.Ticks - LastTimestamp));
                }
            }
        }
    }

Using the code above, here is an example of latencies on a box with 8 cores /w hyperthreading enabled (i.e. 16 cores in Task Manager) and 32 threads (*2x Xeon5550/Gainestown; 4 physical cores per processor; HT Enabled):

![Latency using Monitor.PulseAll(), sample code][2]

EDIT: To try to take NUMA out of the equation, below is a graph running the sample program with 16 threads on a Core i7-3770 (Ivy Bridge); 4 Physical Cores; HT Enabled:

![Latency using Monitor.PulseAll(), sample code, no NUMA][3]

**Can anyone explain why Monitor.PulseAll() behaves in this way?**

EDIT2:

To try and show that this behavior isn&#39;t inherent to waking up a bunch of threads at the same time, I&#39;ve replicated the behavior of the test program using Events; and instead of measuring the latency of PulseAll() I&#39;m measuring the latency of ManualResetEvent.Set().  The code is creating a number of worker threads then waiting for a ManualResetEvent.Set() event on the same ManualResetEvent object.  When the event is triggered, they take a latency measurement then immediately wait on their own individual per-thread AutoResetEvent.  Well before the next iteration (500ms before), the ManualResetEvent is Reset() and then each AutoResetEvent is Set() so the threads can go back to waiting on the shared ManualResetEvent.

I hesitated posting this because it could be a giant red hearing (I make no claims Events and Monitors behave similarly) plus it&#39;s using some absolutely terrible practices to get an Event to behave like a Monitor (I&#39;d love/hate to see what my co-workers would do if I submitted this to a code review); but I think the results are enlightening.

This test was done on the same machine as the original test; a 2xXeon5680/Gulftown; 6 cores per processor (12 cores total); Hyperthreading disabled.

![ManualResetEventLatency][4]

If it&#39;s not obvious how radically different this is than Monitor.PulseAll; here is the first graph overlaid onto the last graph:

![ManualResetEventLatency vs. Monitor Latency][5]

The code used to generate these measurements is below:

    using System;
    using System.Collections.Generic;
    using System.Linq;
    using System.Text;
    using System.Threading;
    using System.Threading.Tasks;
    using System.Collections.Concurrent;
    using System.Diagnostics;
    
    namespace MRETest
    {
        class Program
        {
            static long LastTimestamp;
            static long Iteration;
            static ManualResetEventSlim MRES = new ManualResetEventSlim(false);
            static List&lt;ReadLastTimestampAndPublish&gt; Publishers = 
                new List&lt;ReadLastTimestampAndPublish&gt;();
            static Stopwatch s = new Stopwatch();
            static ConcurrentBag&lt;Tuple&lt;long, long&gt;&gt; IterationToTicks = 
                new ConcurrentBag&lt;Tuple&lt;long, long&gt;&gt;();
    
            static void Main(string[] args)
            {
                long numThreads = 24;
                s.Start();
    
                for (int i = 0; i &lt; numThreads; ++i)
                {
                    AutoResetEvent ares = new AutoResetEvent(false);
                    ReadLastTimestampAndPublish spinner = new ReadLastTimestampAndPublish(
                        new AutoResetEvent(false));
                    Task.Factory.StartNew(spinner.Spin, TaskCreationOptions.LongRunning);
                    Publishers.Add(spinner);
                }
    
                for (int i = 0; i &lt; 20; ++i)
                {
                    ++Iteration;
                    LastTimestamp = s.Elapsed.Ticks;
                    MRES.Set();
                    Thread.Sleep(500);
                    MRES.Reset();
                    foreach (ReadLastTimestampAndPublish publisher in Publishers)
                    {
                        publisher.ARES.Set();
                    }
                    Thread.Sleep(500);
                }
    
                Console.WriteLine(String.Join(&quot;\n&quot;,
                    from n in IterationToTicks where n.Item1 == 10 orderby n.Item2
                        select ((decimal)n.Item2) / TimeSpan.TicksPerMillisecond));
                Console.Read();
            }
    
            class ReadLastTimestampAndPublish
            {
                public AutoResetEvent ARES { get; private set; }
    
                public ReadLastTimestampAndPublish(AutoResetEvent ares)
                {
                    this.ARES = ares;
                }
    
                public void Spin()
                {
                    while (true)
                    {
                        MRES.Wait();
                        IterationToTicks.Add(Tuple.Create(Iteration, s.Elapsed.Ticks - LastTimestamp));
                        ARES.WaitOne();
                    }
                }
            }
        }
    }


  [1]: http://i.stack.imgur.com/ppO9W.png
  [2]: http://i.stack.imgur.com/OmlLs.png
  [3]: http://i.stack.imgur.com/Ebm2k.png
  [4]: http://i.stack.imgur.com/LLrQQ.png
  [5]: http://i.stack.imgur.com/2CLG2.png

Why does Monitor.PulseAll result in a &quot;stepping stair&quot; latency pattern in signaled threads?

I have the `Python` code:

    from multiprocessing import Process
    
    def f(name):
        print &#39;hello&#39;, name
    
    if __name__ == &#39;__main__&#39;:
        for i in range(0, MAX_PROCESSES):
            p = Process(target=f, args=(i,))
            p.start()

which runs well. However, `MAX_PROCESSES` is variable and can be any value between `1` and `512`. Since I&#39;m only running this code on a machine with `8` cores, I need to find out if it is possible to limit the number of processes allowed to run at the same time. I&#39;ve looked into `multiprocessing.Queue`, but it doesn&#39;t look like what I need - or perhaps I&#39;m interpreting the docs incorrectly.

**Is there a way to limit the number of simultaneous `multiprocessing.Process`s running?**


Using multiprocessing.Process with a maximum number of simultaneous processes

I have started learning synchronization in threading.

Synchronized method: 

    public class Counter {
    
       private static int count = 0;
    
       public static synchronized int getCount() {
          return count;
       }
    
       public synchronized setCount(int count) {
          this.count = count;
       }
    
    }


Synchronized block:


    public class Singleton {
    
       private static volatile Singleton _instance;
    
       public static Singleton getInstance() {
          if (_instance == null) {
             synchronized(Singleton.class) {
                if (_instance == null)
                   _instance = new Singleton();
             }
          }
          return _instance;
       }
    }

When should I use `synchronized` method and `synchronized` block?

Why is `synchronized` block better than `synchronized` method ?

Why is synchronized block better than synchronized method?

I&#39;m slightly confused about whether multithreading works in Python or not. 

I know there has been a lot of questions about this and I&#39;ve read many of them, but I&#39;m still confused. I know from my own experience and have seen others post their own answers and examples here on StackOverflow that multithreading is indeed possible in Python. So why is it that everyone keep saying that Python is locked by the GIL and that only one thread can run at a time? It clearly does work. Or is there some distinction I&#39;m not getting here? 

Many posters/respondents also keep mentioning that threading is limited because it does not make use of multiple cores. But I would say they are still useful because they do work simultaneously and thus get the combined workload done faster. I mean why would there even be a Python thread module otherwise?

**Update:**

Thanks for all the answers so far. The way I understand it is that multithreading will only run in parallel for some IO tasks, but can only run one at a time for CPU-bound multiple core tasks.

I&#39;m not entirely sure what this means for me in practical terms, so I&#39;ll just give an example of the kind of task I&#39;d like to multithread. For instance, let&#39;s say I want to loop through a very long list of strings and I want to do some basic string operations on each list item. If I split up the list, send each sublist to be processed by my loop/string code in a new thread, and send the results back in a queue, will these workloads run roughly at the same time? Most importantly will this theoretically speed up the time it takes to run the script? 

Another example might be if I can render and save four different pictures using PIL in four different threads, and have this be faster than processing the pictures one by one after each other? I guess this speed-component is what I&#39;m really wondering about rather than what the correct terminology is.

I also know about the multiprocessing module but my main interest right now is for small-to-medium task loads (10-30 secs) and so I think multithreading will be more appropriate because subprocesses can be slow to initiate. 

Does Python support multithreading? Can it speed up execution time?

I am trying to make a linux executable as a service

I execute my program like this below

    java -jar mytestprogram.jar

creates a process that runs continuously and serves REST requests. But I want to run it as a service where I can do

    service mytestprogram start
    service mytestprogram stop
    service mytestprogram status
    chkconfig mytestprogram on

etc. What is the most simple way of doing it?


Linux: process into a service

What exactly are `process` and `update` in PrimeFaces `p:commandXxx` components and `execute` and `render` in `f:ajax` tag?

Which works at the time of validation? What does `update` attribute do rather than updating value to component from back end? Do `process` attribute bind value to model? What exactly do `@this`, `@parent`, `@all` and `@form` in both attributes?

The example below is working fine, but I am a little confused in basic concepts.
     
    &lt;p:commandButton process=&quot;@parent&quot;
                     update=&quot;@form&quot;
                     action=&quot;#{bean.submit}&quot; 
                     value=&quot;Submit&quot; /&gt;

Understanding PrimeFaces process/update and JSF f:ajax execute/render attributes

I have been developing an app for 1 or 2 weeks now and just yesterday I have updated my iPhone 5S to the iOS 8 GM. Everything worked fine and I could test on my device as well until I deleted the app from my phone and wanted to build again. The following error appeared:

    Could not launch &quot;My App&quot;
    process launch failed: Security

[![Screenshot added][1]][1]

When I test with the simulator it works fine.
Is this because of the iOS 8 GM update and how can I fix this launch problem?
I want to be able to test on my iPhone and in the simulator.


  [1]: http://i.stack.imgur.com/TzLwB.png

Xcode process launch failed: Security

I am using node.js to create a web application. When I run the application (either by opening index.html on the browser or using the command &quot;npm start&quot; on the terminal) I get two errors:    


Uncaught ReferenceError: process is not defined    


Uncaught ReferenceError: require is not defined

I solved the &quot;require is not defined&quot; error by specifically including in my index.html head tag the link to [this][1] script, where the require function is defined.
However, I cannot find something similar for the process function.

My question is doublefold:

1. Why do built-in node.js modules need to be re-defined? Why are they not recognized as they are, that is &quot;built-in modules&quot;? Doesn&#39;t the term &quot;built-in module&quot; mean that a module need not be redefined externaly/second-handedly?

2. Is there a way to solve this problem? My script is very simple, I am just trying to use a basic function of node.js, so I cannot figure out what errors I might have done.

If anyone has come about this problem and has found a way around it or a reason this happens, you would be of great help.


  [1]: http://requirejs.org/docs/release/2.1.17/r.js

Uncaught ReferenceError: process is not defined

```
tcp    0     0 0.0.0.0:80     0.0.0.0:*     LISTEN      9631/node    
```


How do I kill this process in linux(ubuntu)?


How to kill a nodejs process in Linux?

It is said that docker is not a VM and containers directly run on the host.

But why do containers need a base image OS ？

If process in containers run on the base image OS , what&#39;s the difference between a VM and docker(only the base image OS can be re-used and kept read-only?)

And why does it boot faster than a VM?

What makes up a base image OS ? kernel , rootfs or both?



docker is not VM , why container need base image OS ？

I am going through the topic of virtualization and i am totally sucked up understanding the basic concept, Wikipedia does provide some relevant information, but it is not good enough for me to understand the basic idea. The concept will be of 2 to 3 line, but neither I am able to find them on net, nor on the book. 

I will be pleased if someone gives me a basic understanding of these three types. I am well aware of virtualization and understand it well, but these 3 types... 

What is the difference between Full, Para and Hardware assisted virtualization?

How do you run a program all by itself without an operating system running?
Can you create assembly programs that the computer can load and run at startup, e.g. boot the computer from a flash drive and it runs the program that is on the CPU?

How to run a program without an operating system?

I need to find the OS name and version on Unix/Linux platform. For this I tried following:

1. `lsb_release` utility

2. `/etc/redhat-release` or specific file

But it does not seem to be best solution as LSB_RELEASE support is no longer for RHEL 7.

Is there any way that will work on any Unix or Linux platform?

Best way to find os name and version in Unix/Linux platform

Suppose I know the process ID.  I want to find the process name by its ID, using windows batch script.  How can I do this?

Find Process Name by its Process ID

I want to format date as `mm/dd/yyyy`. I tried the following and none of it works for me.
Can anyone help me with this?

reference: [ui-date][1]

    &lt;input ui-date ui-date-format=&quot;mm/dd/yyyy&quot; ng-model=&quot;valueofdate&quot; /&gt; 

    &lt;input type=&quot;date&quot; ng-model=&quot;valueofdate&quot; /&gt;


  [1]: https://github.com/angular-ui/ui-date

How to format date in angularjs

I have three date formats: `YYYY-MM-DD`, `DD.MM.YYYY`, `DD/MM/YYYY`.

Is it possible to validate and parse strings such as `2014-05-18` or `18.5.2014` or `18/05/2019`?

How to format date string via multiple formats in python

Is there a way to get `number.toLocaleString()` with 4 digits after the comma?

Example:

    var number = 49.9712;
    document.getElementById(&#39;id&#39;).innerText = number.toLocaleString();

Result:
**49,9712** 

But now it always returns number with 2 digits after comma:
**49,97** 

JavaScript Number.toLocaleString() with 4 digits after separator

To be honest `go` has spoiled me. With `go` I got used to having a strict formatting standard that is being enforced by my editor (vim) and is almost accepted and followed by everybody else on the team and around the world.

I wanted to format JSON files on save the same way. 

Question: How to auto format/indent/lint json files on save in vim.


How to auto format JSON on save in Vim

How can I format the time elapsed from seconds to hours, mins, seconds? 

My code:

    start = time.time()
    ... do something
    elapsed = (time.time() - start)

Actual Output:

    0.232999801636

Desired/Expected output:

    00:00:00.23 

Content Type	Original Author	Original Content on Stackoverflow
Question	Computernerd	View Question on Stackoverflow
Solution 1 - Multithreading	Dieter Meemken	View Answer on Stackoverflow

Why was the comment that said "Don't format a floppy at the same time" funny when talking about threads and processes?

Multithreading Problem Overview

Multithreading Solutions

Solution 1 - Multithreading

Rename multiple files, but only rename part of the filename in Bash

Symfony2 and date_default_timezone_get() - It is not safe to rely on the system's timezone settings

Attributions