Remote mining of Internet bar

1. The simulator can't dig a mine. If it can, it can't dig a coin even if the mobile phone is scrapped

2. It's not worth it

bitcoin is no longer easy to dig, and it is much cheaper than before

maybe you can only dig for a few hours a day and lose money

even if you mine with a high configuration computer in your own home, it is estimated that you will consume a little more electricity, not counting the aging depreciation of the computer.

3. Now there are many online platforms for mining, just need to register with mobile phone, I know a few good ones

4. It's not worth it

bitcoin is no longer easy to dig, and it is much cheaper than before

maybe you can only dig for a few hours a day and lose money

even if you mine with a high configuration computer in your own home, it is estimated that you will consume a little more electricity, not counting the aging depreciation of the computer.

5. You are being paranoid. Take medicine and sleep!

6. Mars rescue, mining Trojan horse has been around for a long time... Mining Trojan horse has been out in the lower left corner of 360 for protection

7.

Take the SEC's social e-commerce chain, which is a digital asset I often use, as an example. We can check the SEC on the non trumpet of the digital currency market. We can see that the SEC has landed on two exchanges, one is fcoin, and the other is coin egg. However, the prices of the two exchanges are different. Take the figure as an example, if you want to move bricks, you can buy the SEC with a lower price in fcoin first, Then sell it on the higher price coin eggs. After decting the handling charges, you can get a certain difference. The operation of moving bricks is to move bricks. Of course, if you can't move bricks well, you will encounter the change of platform difference. There is still a certain risk ~

8. Basically, the nature is similar, but this is voluntary, which is now called virtual currency, but the state does not recognize it.

9. The difference between redis and memcached is that the traditional MySQL + memcached architecture has encountered problems. In fact, MySQL is suitable for massive data storage. Through memcached, hot data is loaded into the cache to speed up access. Many companies have used this architecture before, but with the continuous increase of business data volume and access volume, We have encountered many problems: 1. MySQL needs to be constantly disassembled, and memcached needs to be constantly expanded. The expansion and maintenance work takes up a lot of development time. 2. Data consistency between memcached and mysql. 3. The hit rate of memcached data is low or the machine is down, and a large number of accesses directly penetrate into dB, which cannot be supported by mysql. 4. Cross machine cache synchronization. There are many NoSQL procts in full bloom. In recent years, many kinds of NoSQL procts have sprung up in the instry. How to use these procts correctly and maximize their advantages is a problem that we need to study and think deeply. In the final analysis, the most important thing is to understand the positioning of these procts and the tradeoff of each proct, In practical application, these NoSQL are mainly used to solve the following problems: 1. A small amount of data storage, high-speed read-write access. This kind of proct ensures high-speed access by means of all data in-motion, and provides the function of data landing. In fact, this is the main application scenario of redis. 2. Massive data storage, distributed system support, data consistency guarantee, convenient cluster node add / delete. 3. Dynamo and BigTable are the most representative papers in this field. The former is a completely decentralized design, in which cluster information is transmitted between nodes through gossip mode to ensure the final consistency of data. The latter is a centralized scheme design, which guarantees strong consistency through a distributed lock service. Data is written to memory and redo log first, and then is periodically compated to disk, optimizing random writing to sequential writing, Improve write performance. 4. Schema free, auto sharding, etc. For example, some common document databases support schema free, directly store JSON format data, and support auto sharding and other functions, such as mongodb. Facing these different types of NoSQL procts, we need to choose the most suitable proct according to our business scenarios. Redis is suitable for scenarios. How to use it correctly has been analyzed before. Redis is most suitable for all data in momory scenarios. Although redis also provides persistence function, it is actually more of a disk backed function, which is quite different from persistence in the traditional sense. Then you may have doubts. It seems that redis is more like an enhanced version of memcached, So when to use memcached and redis? If we simply compare the differences between redis and memcached, we can get the following views: 1 redis not only supports simple K / V data, but also provides list, set, Zset, hash and other data structures. 2. Redis supports data backup, that is, data backup in master slave mode. 3. Redis supports data persistence. It can keep the data in memory on the disk, and can be loaded again when it is restarted. Apart from these, we can go deep into the internal structure of redis to observe more essential differences and understand the design of redis. In redis, not all data are always stored in memory. This is the biggest difference from memcached. Redis will only cache all the key information. If redis finds that the memory usage exceeds a certain threshold, it will trigger the swap operation. According to the "swap ability = age * log (size)_ in_ It calculates which values of the keys need to be swap to the disk. Then the values corresponding to these keys are persisted to the disk and cleared in the memory. This feature enables redis to keep more data than its own memory size. Of course, the memory of the machine itself must be able to hold all the keys. After all, the data will not be swap. At the same time, when redis swips the data in memory to the disk, the main thread providing the service and the sub thread performing the swap operation will share this part of the memory. Therefore, if the data requiring swap is updated, redis will block the operation until the sub thread completes the swap operation. Before and after using redis's unique memory model: VM off: 300K keys, 4096 bytes values: 1.3g usedvm on: 300K keys, 4096 bytes values: 73m usedvm off: 1 million keys, 256 bytes values: 430.12m usedvm on: 1 million keys, 256 bytes values: 160.09m usedvm on: 1 million keys, values as large as you want, Still: 160.09m used when reading data from redis, if the value corresponding to the read key is not in memory, redis needs to load the corresponding data from the swap file, and then return it to the requester. There is an I / O thread pool problem. By default, redis will be blocked, that is, it will not be blocked until all the swap files are loaded. This strategy is suitable for batch operation when the number of clients is small. However, if redis is applied in a large website application, it is obviously unable to meet the situation of large concurrency. So when redis is running, we set the size of the I / O thread pool to perform concurrent operations on the read requests that need to load the corresponding data from the swap file to rece the blocking time. If you want to use redis in the environment of massive data, I believe it is indispensable to understand the memory design and blocking of redis. Additional knowledge points: comparison between memcached and redis 1 network IO model memcached is a multithreaded, non blocking IO multiplexing network model, which is divided into monitor main thread and worker sub thread. The monitor thread monitors network connection, and after receiving the request, passes the connection description word pipe to the worker line to read and write io. The network layer uses the event library encapsulated by libevent, Multithreading model can play the role of multi-core, but it introces cache coherence and lock problems. For example, stats command is the most commonly used command in memcached. In fact, all operations of memcached have to lock and count the global variable, which brings performance loss (memcached network IO model) redis uses the IO reuse model of single thread and encapsulates a simple aeevent event processing framework. It mainly implements epoll, kqueue and select. For simple IO only operations, single thread can maximize the speed advantage, but redis also provides some simple computing functions, such as sorting, aggregation, etc, The single thread model will seriously affect the overall throughput. In the process of CPU computing, the entire IO scheling is blocked. 2. In the aspect of memory management, memcached uses pre allocated memory pool, using slab and chunk of different sizes to manage memory, and item selects appropriate chunk storage according to size. Memory pool can save the cost of applying / releasing memory, and rece the generation of memory fragmentation, but it also brings a certain degree of space waste, In addition, when there is still a lot of memory space, new data may also be eliminated. For the reasons, please refer to timyang's article (memcached /). There are many client software implementations of memcached, including C / C + +, PHP, Java, python, ruby, Perl, Erlang, Lua, etc. Currently, memcached is widely used, including Wikipedia, Flickr, twitter, youtube and WordPress, in addition to livejournal. Under the window system, the installation of memcached is very convenient. Just download the executable software from the address given above, and then run memcached.exe – D install to complete the installation. In Linux and other systems, we first need to install libevent, and then get the source code from make & make install. By default, the server startup program of memcached is installed in the / usr / local / bin directory. When starting memcached, we can configure different startup parameters for it. 1.1 configuration of Memcache key parameters need to be configured ring the startup of the memcached server. Let's take a look at the key parameters that need to be set ring the startup of memcached and the functions of these parameters. 1) - p the TCP listening port of memcached. The default configuration is 11211; 2) - U memcached's UDP listening port. The default configuration is 11211. When it is 0, UDP listening is turned off; 3) UNIX socket path monitored by - s memcached; 4) - A is the octal mask for accessing UNIX socket. The default configuration is 0700; 5) - l the IP address of the monitored server, which is all network cards by default; 6) - d starts the daemons for the memcached server; 7) - R maximum core file size; 8) - u the user running memcached. If it is currently root, you need to use this parameter to specify the user; 9) - m the amount of memory allocated to memcached, in MB; 10) - M indicates that memcached returns an error when the memory is used up, instead of using LRU algorithm to remove data records; 11) - C maximum number of concurrent connections, the default configuration is 1024; 12) - V – VV – VVV sets the detail level of messages printed by the server, where - V only prints error and warning information, - VV will print client's commands and corresponding information on the basis of - V, - VV will print memory state transition information on the basis of - VV; 13) - F is used to set the increment factor of chunk size; 14) - n the minimum chunk size, which is 48 bytes by default; 15) - t the number of threads used by memcached server. The default configuration is 4; 16) - l try to use large memory page; 17) - r the maximum number of requests per event, which is 20 by default; 18) - C disable CAS, CAS mode will bring 8 bytes rendancy; 2. Introction to redis redis is an open source key value storage system. Similar to memcached, redis stores most of the data in memory. The data types it supports include string, hash table, linked list, set, ordered set and related operations based on these data types. Redis is developed in C language and can be used on most POSIX systems such as Linux, BSD and Solaris without any external dependencies. Redis also supports rich client languages. Common computer languages such as C, C #, C + +, Object-C, PHP, python, Java, Perl, Lua, Erlang, etc. all have available clients to access redis server. At present, redis has been widely used, such as Sina and Taobao in China, Flickr and GitHub in foreign countries. The installation of redis is very convenient. Just download it from the bin directory. When starting the redis server, we need to specify a configuration file for it. By default, the configuration file is in the redis source directory, and the file name is redis.conf. The difference between Memcache and redis in PHP interview questions

10. It's not worth it. Now it's hard to dig red currency, and it's much higher than before. Competition is too big, you may dig a day is only enough for a few hours of Internet fees, will lose. Even if you mine with a high configuration computer in your own home, it is estimated that it will cost a little more than electricity, not counting the aging depreciation of the computer.