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one. JSON moduleSerialization: Changing the shape of an object so that he can be stored in a file or transmitted over a network, serialization is called persistence, which is to store objects in permanent media, so that they are not lost due to power loss. JSON (JavaScript Object Notation) is a lightweight data interchange format, JSON is used to convert strings and Python data types, and the JSON module provides four functions: dumps, dump, loads, lo

high memory usage and high CPU usage.In the hang mode, the dump file is crawled in a non-intrusive manner and does not interrupt the thread, so it is not necessary to have the same identity as the boot process, which is useful when the client is debugging the server with the Hang mode fetching dump file. -crash Fetch dump file When the process terminates abnormally.There are 3 scenarios where the process terminates abnormally:1.unhandled of exceptionThe 2.asp.net process term

an object.How do---serialize?Two modules are available in Python for serialization. Are pickle and JSON, respectively.PicklePickle is a unique serialization module in Python, so-called exclusive, which means that it cannot interact with the serialization of other programming languages because pickle converts the data object to bytes>>> Import pickle>>> d=[1,2,3,4]>>> pickle.dumps (d) B ' \x80\x03]q\x00 (k\x01k\x02k\x03k\ x04e. ' >>> type (Pickle.dumps (d)) The Pickle module provides four functi

expiration, and more.Here's the official Bench-mark data:The test completed 50 concurrent executions of 100,000 requests.The set and get value is a 256-byte string.Linux box is running Linux 2.6, which is X3320 Xeon 2.5 GHz.Text execution uses the loopback interface (127.0.0.1).Result: The write speed is 110,000 times/s, the reading speed is 81,000 times/s.Redis Common commands:In the case of DB, Redis scores have been amazing, and not to mention the Memcachedb and Tokyocabinet, the original me

JSON general-purpose data structures in Python are dictionaries and lists * * *# # Json:four_leaf_clover:Used to convert between a string and a Python data type, because JSON represents a stringThe JSON module provides four methods| Method | Description || ----- | ----------------------------- || Dump | Receives a file handle and converts the original data type to a string to write to the file || Load | Receives a file handle that converts a string in a file to the original data type returned |

1. Base content: ALTER SESSION SET EVENTS ' immediate trace name buffers level n '; N Value Meaning: 1 dumps the buffer header only. 2 Dumps the data block on a level 1 basis. 3 The data block content is then dumped on a level 2 basis. 4 Dump buffer header and hash chain. 5 Dumps the data block and hash chain on a level 1 basis. 6 The data

;However, it is best to verify the (-D parameter) with the debug option before it is formally executed, which is also important for debugging#/usr/sbin/logrotate-f/etc/logrotate.d/nginx//not to time or not to cutting conditions, forced cutting#/usr/sbin/logrotate-d-f/etc/logrotate.d/nginx//Output cutting debug informationSo far, we know how Logrotate realizes automatic cutting logs.Logrotate Configuration CasesNginx Common Log Cutting configuration/data/log/nginx/*.log/data/log/nginx/*/*.log {#

log, records user and workgroup transformation, user login authentication information, and/var/log/ Btmp records the user, time, and remote IP address of a Linux login failure, while/var/log/cron records the execution of scheduled tasks.The Syslog service is managed by two important configuration files, namely the/etc/syslog.conf Master profile and the/etc/sysconfig/syslog secondary configuration file, while/etc/init.d/syslog is the startup script.When the system is working for a certain period

:",data_stringOutput:DATA: [{‘a‘:‘A‘,‘c‘:3.0,‘b‘:(2,4)}] #python的dict类型的数据是没有顺序存储的JSON: [{"a":"A","c":3.0,"b":[2,4]}] The output of JSON is similar to data, except for some subtle changes such as Python's tuple type becoming an array of JSON, the code conversion rules for Python to JSON are:The Json.loads method handles decoding (decoding) conversions of simple data typesimport jsondata = [{‘a‘:"A",‘b‘:(2,4),‘c‘:3.0}] #list对象data_string = json.dumps(data)print "ENCODED:",data_stringdecoded = j

1,JSON module load/loads, Dump/dumps difference: (excerpt from here)JSON is actually a string representation of a Python dictionary, but a dictionary as a complex object is a string that cannot be converted directly into the code that defines it, and Python has a library called Simplejson that makes it easy to generate and parse JSON. This package is already contained in python2.6, which is called JSON consists of four methods: Dump and

normal data types, json.loads and eval, but when it comes to special types, eval doesn't work. So the focus of eval is usually to execute a string expression and return the value of the expression.code example:This example can be changed as follows:Import Jsonx = "[none,true,false,1]" Print (eval (x))Two modules for serialization:JSON, used to convert between string and Python data typesPickle for conversion between Python-specific types and Python data typesThe JSON module provides four functi

before, then pull from the site, and into the cache. The code is as follows: Copy Code code as follows: def get_dump_data (dir_name, URL): m = hashlib.md5 (URL) filename = M.hexdigest () Full_file_name = \ ' dumps/%s/%s\ '% (dir_name,filename) If Os.path.isfile (full_file_name): Return eval (file (full_file_name,\ ' r\ '). Read ()) Else Return None def set_dump_data (dir_name, URL, data): If not os.path.isdir (\ '

seconds, that is, we apply for an exclusive latch lock on page (1:19,239), but applied for 300 seconds (5 minutes), or did not apply. Here the flags are used to determine whether the latch is superlatch, and for the analysis latch Wait is not useful, so we do not further specific analysis. The task address and the owning task address are important in memory dump analysis. Especially the owning task, which is the task that blocks other processes from acquiring latch locks. "How To fix" Latch app

modules is loaded. If you were just curious about the internals of SQL Server, this is the type of dump you want to create. Using A debugger, such aswindbg, you can analyze a dump file. Remember that is looking at a snapshot in time of the process–but even then, just showing the call stacks can be quite enlightening. INNBSP;WINDDG, the command to show all call stacks is:~*kn. If you is the kind of person who likes to has a mental model of how a product works–minidump can help you deepen

Export the database data1 to a file in the shell with Command pg_dumppg_dump-d data1-f Test.txtOrpg_dump-d data1 > Test.sqlAnd then create an empty libraryCreatedb data2Import data1 data into data2 with the Psql commandpsql-d data2-D data2 Pg_dump More informationPg_dump dumps a database into plain text files or other formats.Usage: pg_dump [options] ... [Database name]General Options:-F,--file=filename output file or directory name-F,--format=c|d|t|

Pg_restore to choose what to restore, or even reorder the items that need to be recovered before resuming. Archive files can also be ported across platforms.D:\Program Files\powercmd>pg_dump--helpPg_dump dumps a database into plain text files or other formats.Usage: pg_dump [options] ... [Database name]General Options:-F,--file=filename output file or directory name-F,--format=c|d|t|p output file format (custom, directory, tar, plain text)-V,--verbos

save for the moment, is interested in the search engine):>>> Collection.replace_one (old_document, new_document)4.4 Delete:>>> Collection.remove (temp)//Even if the temp does not exist, there will be no error >>> collection.delete_one (temp) >> > Collection.delete_many (temp)//differs from. Insert_many () and does not error when temp is not a list typeAdd:1.JSON serialization and deserialization:If you want to serialize to a standard JSON format, two ways, one way ,

‘: [ValidationError([‘未选择你的选项‘])], ‘__all__‘: [ValidationError([‘用户名和备注的内容不能一样‘])]}For the ValidationError type, we only need the messages and code, respectively, the error message and the type of error. There is a need to customize the class to serialize instead of the dumps method:from django.core.exceptions import ValidationErrorclass JsonCustomEncoder(json.JSONEncoder): def default(self, field): if isinstance(field, ValidationError):

function.JsonJSON provides four functions: Dumps,dump,loads,load (the first two are for serialization, and two for deserialization)First, let's take a look at whether you can implement a file operation without JSON serializationWe create a file and store it in a dictionary to see if it's okay.The result?Obviously the error, tell us that the content written into the file must be a string format, not a dictionary.We're trying to write with the JSON mod

tool because it is easy to use and comes with a JDK. Since it is a terminal-based tool, we can write some scripts to generate thread dumps periodically for analysis. Read this document to learn more about generating thread dumps.23. What is a deadlock (Deadlock)? How do I analyze and avoid deadlocks?Deadlocks are situations in which more than two threads are permanently blocked, which results in a minimum