Wen: idle
Source: Python Technology [official ID: PYTHonAll]
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Afternoon and wife hand in hand heart to heart to “good time” photo studio to take photos, record our beautiful moment.
After taking a group of photos, when I was waiting for the photographer to repair the picture, my wife stood behind me and gave me a pat on the back, saying that I was hard driving, and rubbed my shoulder and beat my back. The treatment is really enviable to passers-by a, as a man, this satisfaction is unparalleled.
At this time, as a man, WE are not to be outdone: take out the phone, open wechat, click “transfer”, input 520, transfer message does not forget to add a “mo mo da”.
After a stretch, I remind my wife to quickly see the micro channel, the wife opened the micro channel, brush a few times, what did not see, came to ask me to say, what to see?
I raise a voice to say: gave you hair a big bag, you hurriedly took, out of date do not wait ha!
Where can I get a big bag? Look at that! I didn’t get anything!
Hear this sentence, I leng once, immediately braved a cold sweat: have not received? Did I send it to the wrong person? Finished finished, hurriedly check, if sent to another girl’s micro letter jumped into the Yellow River also wash not clear!
I quickly turned on my phone and confirmed three times that it was correct, which was a sigh of relief. I said you see, I have sent the past, you did not receive, you are not good signal, you connect WiFi to see!
Wife connected WiFi, also did not see. I open the mobile phone micro blog, refresh the content is no problem, psychological 100 why…
At this time, the owner of the photo repair lady (said to be like a certain star) said to us, the photo is fixed, let us have a look. After we saw it, we said we were very satisfied, and changed my serious expression into a smile. It was great!
Then the owner’s wife asked me to add her wechat and send me the film. I scanned the QR code on wechat and added wechat. But the owner’s wife waited a long time, also did not receive the friend request. I added it again and I got the same result. I do not believe evil, switched to another unicom 5G card, and added, the result is also not received.
I am depressed, this is 4G plus 5G, a total of 9G, how still can not receive the request?
The result lets the wife add, once was successful.
At that time the thief is depressed, the red envelope wife of showing off did not receive, the micro letter of star boss wife also did not add, today this character is how?
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After carelessly finish, we left the studio, wife on the road also say a red envelope, looking at her pathetic appearance, I love dearly, so I picked up the phone to turn a 520 in the past, in order to distinguish, I specially in the transfer message after adding a penguin hair heart expression.
This time she saw the past, with the potential point of the red envelope. Unexpectedly, after she received the red envelope, another appeared immediately, that is, the one that had not been received before, at this time also appeared. No surprise, in order to grab the red envelope hand speed immediately again point once, ecstatic to say to me: thank husband, two red envelopes have received!
This kill a thousand knife of wechat, harm ah! Wechat balance only a total of more than 1000, this suddenly emptied, how to live the next day! Can you understand my inner OS at this time?
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In the evening, I went back home to brush weibo, and accidentally found that “wechat bug” was trending. When I saw the official Weibo of wechat, I knew THAT I had been cheated by wechat:
The wechat team said that at around 14:00 today, some wechat users experienced a delay in receiving messages due to system jitter, which has been fixed.
The wechat team also reassured everyone that there should be no problem with your network.
I thought to myself: my family network is no problem, my family harmony almost suffered!
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After reading this explanation, as a technical person, my first reaction was of course to understand what “system jitter” is. I went to the Internet to search for relevant information, and the explanation was as follows:
If a low-priority process is assigned fewer frames than the minimum required by the computer architecture, the process must be suspended. Then, all of its remaining pages should be called up so that all allocated frames can be released. This regulation introduces a swap in/out layer for intermediate CPU scheduling.
In fact, you need to look at the process of not having “enough” frames. If the process does not have the number of frames needed to support the active use of the page, it will quickly produce a page missing error. At this point, a page must be replaced. However, since all of its pages are in use, the pages that need to be used again must be replaced immediately. So, again, it quickly produces a page missing error, and again replaces the page that must be returned immediately, so quickly.
This high level of page scheduling activity is called jitter. If a process takes more time to paging than it takes to execute, the process is shaking.
What causes the system jitter?
The operating system monitors CPU usage. If CPU utilization is too low, increase the degree of multichannel by introducing new processes into the system. Using the global replacement algorithm replaces any page, regardless of which process they belong to.
Now assume that the process has entered a new phase of execution and needs more frames. It starts getting page missing errors and getting frames from other processes. However, these processes also need these pages, so they also get page missing errors and get frames from other processes. These page-missing error processes must use paging devices to swap pages in and out. When they are queued for paging devices, the ready queue clears. As the process waits for the paging device, the CPU utilization decreases.
The CPU scheduler sees a decrease in CPU utilization and increases the degree of multichannel. New processes try to get frames from other running processes to start, resulting in more page missing errors and longer paging device queues. As a result, CPU utilization drops further, and the CPU scheduler tries to increase the multichannel degree again. As a result, there is jitter, the system throughput drops sharply, and the page error rate increases significantly. As a result, the effective memory access time increases, and no work gets done because the process is always busy paging.
In this wechat event, our popular understanding is:
Thrashing is a computer term used to describe a phenomenon in virtual memory schemes where memory or other resources are exhausted or limited, resulting in an inability to perform the desired operation.
When this happens, the program makes a request through the operating system, and the operating system tries to call the required resource from another program, causing the new request to go unfulfilled.
When system jitter occurs, system time is spent on slow I/O, swapping pages more than executing instructions, and system efficiency is greatly reduced.
In plain English: the resources of the wechat messaging system are not enough.
Today, although my wallet is empty, I feel that I lost hundreds of millions of dollars, and I almost lost a good thing, but I experienced a major event in wechat, and I learned some new knowledge, which is not a small harvest!
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