java - Write lock degradation problem in read-write lock

When the write lock is downgraded, the thread that has currently acquired the write lock is required to hold the write lock, then acquire the read lock, and then release the write lock. So why is it required to hold the write lock? ? In the above picture, it is mentioned that "then the current ...

大家讲道理 2017-06-12 09:24:17 0  3  1229

linux - How to understand the file access mode Write only in the file descriptor table?

For file descriptors in the operating system, there is a file descriptor table maintained by the kernel at the system level. The status information contained in it includes file access modes. There are three types: read only, write only, read&write. What is the situation of write only? I can ima...

某草草 2017-06-12 09:24:34 0  1  898

mysql_replication - What to do if a single writing database cannot meet the performance requirements when mysql reads and writes are separated?

When mysql reads and writes are separated, what should I do if a single writing database cannot meet the performance? Should I use multiple databases to write? So how to synchronize data and ensure data consistency?

学习ing 2017-06-20 10:05:42 0  2  944

java - Singleton service solves multi-process writing files

Now we need a multi-process program to write files. If we write directly, we need to ensure that the process locks the file handle. Now we want to register a singleton writing service through spring. When multiple programs write files, they request the spring interface to write. Is such a solution f...

天蓬老师 2017-05-17 10:01:08 0  3  1028

vagrant+php+iis writable permission problem

There is currently a project being developed using vagrant (php+windows server 2012+iis). There is an upload function that requires writable permissions on the directory. Because the files synchronized by Vagrant cannot directly modify the permissions. Is there any solution?

大家讲道理 2017-05-16 13:14:12 0  1  469

What to do if writing fails

Warning: file_put_contents(binggege.txt): failed to open stream: Permission denied in /Applications/XAMPP/xamppfiles/htdocs/www/test/open_file.phpon line 4 Writing failed or there is no permission, please check

UI designer 2017-06-28 13:58:40 0  1  1198

mysql - Why does database read-write separation improve database performance?

Please see the blog above for why read-write separation can improve database performance. According to database common sense, read-write separation can indeed improve database performance, but you don't know if you understand its underlying principles. For example, one reads and one writes, but the ...

PHPz 2017-05-24 11:34:46 0  2  1333

How does Python write the results of a loop into a csv file in column order?

I'm a complete novice, so I beg you guys! ! {Code...} The running results are as follows. Now I want to write the results obtained from each loop into a new csv file in turn, but it is best to write them column by column. Thank you very much! ! ! ! ! ! !

过去多啦不再A梦 2017-05-18 10:48:34 0  2  1069

The latest PHP advanced video tutorial in 2017 (2) 7-11 Rewriting the session storage mechanism video cannot be loaded

The latest PHP advanced video tutorial in 2017 (2) 7-11 Rewriting the storage mechanism of session The video cannot be loaded and only displays "Loading error"

phpcn_u89397 2020-08-09 15:53:57 0  0  1100

Encountered a serious problem. User registration cannot write users table data. Error message. The field has no initial value. The steps follow the video and cannot be skipped.

Encountered a serious problem. User registration cannot write users table data. Error message. The field has no initial value. The steps follow the video and cannot be skipped.

小试手笔 2017-09-23 10:03:13 0  2  1188

mysql has a write of 7 or 8MB every 10 seconds

My mysql has a write of 7~8mb every about 10 seconds, usually only a few hundred kb. How can I troubleshoot this problem? The following is a screenshot of the abnormal situation. The following is a screenshot of the normal situation.

伊谢尔伦 2017-06-20 10:05:49 0  2  972

wamp cannot create a virtual host and reports the error hosts is not writable

Wamp cannot create a virtual host and reports an error The file C:/WINDOWS/system32/drivers/etc/hosts is not writable. It feels uncomfortable to watch the teacher succeed. It is too difficult.

Genofer 2019-04-13 12:55:16 0  0  1947

Will Linux report an error when using mv to move files that are being read and written?

1) What will happen if you use the mv command to remove the file being read in the Linux system? For example, file 1.txt is being read by process A. If I use the mv command to move 1.txt to another directory, will process A make an error? 2) What will happen if mv removes the file being written? For...

世界只因有你 2017-05-18 10:51:33 0  2  1879

java - How to access the page under web-inf in the Eclipse project in the browser, is it not possible to access it directly? How to write in the address bar

How to access the page under web-inf in the Eclipse project in the browser? Can't access it directly? How to write in the address bar

ringa_lee 2017-05-17 10:08:22 0  2  747

How to give PHP write permission to a directory?

I'm trying to create a file using PHP but it's not working. I'm assuming this is because it doesn't have write access (has been this problem before). I tried to test if this was the problem by chmod0777ing the folder, but this ended up causing every script in that directory to return a 500 error mes...

P粉512363233 2023-08-27 15:25:11 0  2  608

How to merge multiple txt files in a folder in Python?

Read a txt file in the folder and record the txt file name (user ID) and write it into a new txt file. Delete the original txt file. Delete the above steps. Loop the txt file and sort by time in the content. Add user ID + original content at the beginning of each log.

漂亮男人 2017-05-18 10:54:10 0  1  1139

document.write error

There is no display in the browser according to the typed code, and f12 displays: Uncaught TypeError: Document.write is not a function

ԾvԾ人人余耳总 2019-04-08 21:24:51 0  3  1351

Why is it not hidden when you move the mouse to the second-level menu? jquery writes that when the mouse removes the first-level menu, the second-level menu is hidden.

Why is it not hidden when you move the mouse to the second-level menu? jquery writes that when the mouse removes the first-level menu, the second-level menu is hidden.

L 2018-12-31 19:07:27 0  2  1285

An error occurs when reading the contents of a newly created temporary file

<?php//Create a temporary file $lsfile = tmpfile();//Write data into it $lsshuju = fwrite($lsfile,'111 Here is the data written to the temporary file');//Output the writing situation echo 'Written to the temporary file' . $lsshuju . 'Characters<br>';//Output the contents of the temporary fi...

LIWEN 2017-06-14 15:08:52 0  1  1373

Unable to open newly created domain names and sites

Follow the steps and it will show a page loading error. It cannot be accessed using the domain name. It can be accessed using the 127.0.0.1/demo path.

戚晨阳 2018-03-18 21:41:56 0  1  1226