1、 What is bytecode ? What are the advantages of bytecode ?
2、 Oracle JDK and OpenJDK Comparison of ？
3、Arrays.sort and Collections.sort Implementation principle and difference
4、wait and sleep What's the difference ？
5、 How arrays are allocated in memory ？
6、HashMap 1.7 And 1.8 Of difference , explain 1.8 What optimizations have been made , How to optimize ？
7、HashMap Expansion process
8、HashMap Is it thread safe , Why not thread safe （ It is best to draw a picture to show that multithreaded environments are not safe ）?
9、HashSet How do you make sure you don't repeat ？
10、 Memory model and partition , What to put in each area in detail ？
11、 Partitions in the heap ：Eden,survival （from+ to）, Old age , Their characteristics are ？
12、GC What are the two methods of judging ？
13、SafePoint What is it? ？
14、GC Three collection methods of ： Mark clear 、 Tag to sort out 、 Principle and characteristics of replication algorithm , Where to use them separately , If you want to optimize the collection method , What's the idea ？
15、GC What are the collectors ？CMS Collector and G1 Characteristics of collector .
16、Minor GC And Full GC When do they happen ？
17、JVM What are the areas of memory , What is the role of each zone ?
18、 If and judge whether an object is alive ?( perhaps GC The method of judging objects )
19、 sketch java Garbage collection mechanism ?
20、Java What are the methods of garbage collection in ?
21、Java Class loading process ?
22、 sketch Java Class loading mechanism ?
23、 The mechanism of parent delegation model of classloader ？
24、 What is a class loader , What are the class loaders ?
25、 sketch java Memory allocation and recovery policy rate and Minor GC and Major GC.
26、activemq What if the data is not submitted successfully ( Lost message )
27、activeMQ What are the ways to send messages ？
28、activeMQ How to tune ？
29、 What is dead letter queue ？
30、Basic.Reject What is the usage of ？
31、 Why shouldn't all of message All use persistence mechanism ？
32、 Why? heavy RPC It is not recommended to use disk node ？
33、 Under what circumstances producer Don't actively create queue Is safe ？
34、“dead letter”queue Use of ？
35、 stay Join Use examples of a similar type for tables , And index it
36、 And Oracle comparison ,Mysql What are the advantages ？
37、 distinguish CHAR_LENGTH and LENGTH？
38、 stay Mysql in ENUM What is the usage of ？
39、CHAR and VARCHAR The difference between ？
40、 What string types of columns can be ？
41、 How to get the current Mysql edition ？
42、Mysql What storage engine is used in ？
43、TIMESTAMP stay UPDATE CURRENT_TIMESTAMP What to do with data types ？
44、 What's the difference between a primary key and a candidate key ？
45、 How to use Unix shell Sign in Mysql？
46、 myisamchk What is it used for ？
47、MYSQL What are the methods and commands for database server performance analysis ?
48、 How to control HEAP The maximum size of the watch ？
49、MyISAM Static and MyISAM Dynamic What's the difference? ？
50、federated What is a watch ？
51、 If a table has a column defined as TIMESTAMP, What will happen ？
52、 The column is set to AUTO INCREMENT when , If the maximum value is reached in the table , What will happen ？
53、 How to find out which auto increment was allocated at the last insert ？
54、 How do you see all the indexes defined for the table ？
55、LIKE Statement ％ and _ What does that mean? ？
56、 How to be in Unix and Mysql Conversion between timestamps ？
57、 How do we get the number of rows affected by the query ？
58、Mysql Whether the query is case sensitive ？
59、LIKE and REGEXP What's the difference in operation ？
60、BLOB and TEXT What's the difference? ？
61、mysql_fetch_array and mysql_fetch_object What's the difference ？
62、 How we are in mysql Run batch mode in ？
63、MyISAM Where will the forms be stored , And also provides its storage format ？
64、Mysql What are the different tables in ？
65、ISAM What is it? ？
66、InnoDB What is it? ？
67、Mysql How to optimize DISTINCT？
68、 How to input characters as hexadecimal numbers ？
69、 How to display the front 50 That's ok ？
70、BIO、NIO and AIO The difference between ？
71、Netty Characteristics ？
72、Netty Thread model of ？
73、TCP Sticky package / The reason and solution of unpacking ？
74、 How to choose serialization protocol ？
75、NIOEventLoopGroup Source code ？
76、RabbitMQ Medium broker What is it? ？cluster What do you mean ？
77、RAM node and disk node The difference between ？
78、vhost What is it? ？ What's the effect ？
79、 The client connects to cluster Any of the node Is it all working ？
80、 Why? heavy RPC It is not recommended to use disk node ？
81、RabbitMQ Allowed to send message What's the maximum ？
82、 How to prevent blackholed problem ？
83、Basic.Reject What is the usage of ？
84、 Why shouldn't all of message All use persistence mechanism ？
85、RabbitMQ Medium cluster、mirrored queue, as well as warrens What problems are the mechanisms used to solve ？ What are the problems ？
86、NoSQL What are the types of databases ?
87、MySQL And MongoDB What is the basic difference between ?
88、 How do you compare MongoDB、CouchDB And CouchBase?
89、MongoDB Be the best NoSQL What's the reason for the database ?
90、journal Play back in item (entry) When incomplete ( For example, there happened to be a midway fault ) Is there a problem ?
91、 The analyzer is in MongoDB What is the role of ?
92、 Namespace (namespace) What is it? ?
93、 If the user removes the properties of the object , Whether the attribute is removed from the storage tier ?
94、 Can I use the log feature for security backup ?
95、 Allow null value null Do you ?
96、 How to execute a transaction / Lock ?
97、 How long does it take to enable backup recovery ?
98、 What is? master or primary?
99、 I have to call getLastError To make sure that the write operation works ?
100、 How to understand MongoDB Medium GridFS Mechanism ,MongoDB Why use GridFS To store files ？
Sum up the answer
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