Word-wrap: break-word! Important; “> < p style =” max-width: 100%
1. Use junit, before, beforeClass, after, afterClass execution order
2. Distributed lock
3. Nginx request forwarding algorithm, how to configure by weight forwarding
4. What’s wrong with using hashMap to implement Redis (deadlock, loop, ConcurrentHashmap)
5. Thread status
5. The way threads block
6. The difference between sleep and wait
7. Low-level implementation of HashMap
8. Ten thousand people grab 100 red envelopes, how to achieve (no queue), how to ensure that two people can not grab the same red envelope, available distributed lock
Java memory model, garbage collection mechanism, unreachable algorithm
10. Two Integer references are passed to a swap method to swap references within the swap method
11. Aop’s underlying implementation, dynamic proxy is how dynamic, if there are 100 objects, how dynamic proxy for the 100 objects
12. Have you used Maven Install? Maven test. Git (make install)
13. How to configure docBase for tomcat
14. Several ways to configure Spring beans
15. Configuration of web.xml
16. Spring listeners.
17. Implementation mechanism of ZooKeeper, with cache, how to store registration service
18. Does IO block? ReadLine is blocked
19. Spring thread pool or Java thread pool?
20. String formatting methods (20, 21)
What is the timer made of
23. How do threads exit and terminate
24. What locks does Java have? Optimistic lock Pessimistic lock synchronized read/write lock, use reentrantlock Reentrantlock vs. Synmchronized
25. Usage scenarios of ThreadLocal
Java memory model, garbage collection mechanism
27. Why should a thread execute a call to start instead of run?
28. Implementation mechanism of QMQ message (QMQ is qunar’s encapsulated message queue)
29. Three ways to traverse a HashMap
30. Some JVM commands
31. Differences between Memcache and Redis
Mysql > select * from user where row lock is placed
33. How is the lock of ConcurrentHashmap added? The more sections, the better
Innodb isa row lock, myISAM isa table lock.
35. Other performance optimizations for mysql
36. Where can I see Linux system logs
37. How do I view network processes
38. Count the number of bits 1 in the binary representation of an integer
39. JVM memory model, Java memory model
40. How to dump all Java memory data
41. How do I trigger a full garbage collection manually and how do I trigger a garbage collection immediately
42. What happens if a hashmap has only one write and all other reads
43. git rebase
44. Differences between mongodb and hbase
45. How to solve the concurrency problem
46. Uses of volatile
47. Java thread pool
48. mysql的binlog
49. Proxy mode
50. How does mysql implement transactions
51. When is read/write separation mandatory, which secondary library to read is determined by what method, and what method is used to synchronize mysql from secondary libraries
Mysql storage engine
Mysql default isolation level, other isolation levels
54. Reverse a linked list (with three Pointers, but only one at a time)
55. The implementation principle of Spring Aop
56. When a memory leak occurs and what exceptions are thrown by a memory leak
57. Have you used Autowire annotations
58. Spring’s way of injecting beans
59. The execution order of various conditions in SQL statements, such as SELECT, WHERE, Order by, group BY
60. Select xx from xx where xx and xx order by xx limit xx; How to optimize this (see Explain)
61. Write code for the four primitives
62. Collect statistics on the 100 IP addresses that occur most frequently in the 100 GB IP file
63. How to inform the consumer of the failure of zooKeeper’s things, nodes and service providers
64. How to elect a leader for 5 Servers (Election Algorithm)
65. Differences between adapter and proxy patterns
66. The read-write lock
67. The static locking
68. Transaction isolation level
69. Facade Mode, Class Diagram (Facade Mode)
70. How does mybatis map table structure
Binary tree traversal
72. Master/slave replication
73. Mysql engine differences
74. Which section is the static inner class loaded into? Methods area
75. Where the class file was compiled and loaded
76. How does a longer overall response time for HTTP requests on the Web result in fewer requests being processed? With queues, when you can’t handle so many HTTP requests, you put them in queues and process them slowly. How does the Web implement queues
77. Thread-safe singleton pattern
78. Quicksort performance considerations
79. Use of the volatile keyword
80. What storage engine can be used to determine the size of a table or do statistics
81. What engine can read more write less use
82. What engine should be used if you want to count multiple tables
83. How to lock the size of concurrenhashMap, and what to do if the size changes after the length of concurrenhashMap
84. 1000 apples in 10 baskets, how can I get all the possible numbers
85. Reentrant read/write locks. How is reentrant implemented?
86. Have you used NIO
87. Have Java concurrent packages been used
88. Sting s=new String (” ABC “) which objects are created on the stack respectively
89. Region allocation of Java virtual machine, what is stored in each region
90. Distributed Transactions (JTA)
Both threadLocal and Synchonized are used to deal with multi-threaded concurrent access. But ThreadLocal is fundamentally different from synchronized. Synchronized is a mechanism that uses locks to make variables or code blocks accessible only to one thread at a time. ThreadLocal, on the other hand, provides a copy of variables for each thread, so that each thread is not accessing the same object at any one time, thus isolating multiple threads from sharing data. Synchronized, on the other hand, is used to obtain data sharing when communicating between multiple threads.)
92. What containers does Java have (collections, tomcat is a container)
93. Binary search algorithm
What types can be stored in Redis
HTTP protocol format, the difference between GET and POST
97. Wait and notify for reentrant locks
98. Can Redis swap memory space to disk (this should be possible, but the interviewer told me not to)
99. How do cache-based and fixed-length threads handle too many requests in Java thread pools? The queue for fixed length things. What if the queue is full? Swap to disk? What about a cache-based thread pool solution?
100. What lock does synchronized add to methods 101. The difference between lock and trylock in a reentrant lock
102. Can InnoDB read a row of data? Not shackles, read the actual read is a copy
Redis cache is distributed storage? Is the data stored on different servers duplicate? Guava cache? Repeat? Different machines store different data
104. Use awk to collect top10 statistics in an IP file
105. When performing statistics on a table, you can directly view the schema info information, that is, view the system information of the table
The current version of mysql
107. What help did the experienced people in the company give? (This is usually asked by the boss)
108. What advantages do you have over other graduates
109. Give examples of how your good summarization habit has helped you in your future work
110. Atomic classes, thread-safe objects, exception handling
Hash (1, 2, 32) int (1, 2, 32) hash (2, 32) int (1, 2, 32) int (1, 1)
11.14 billion urls, find the duplicate urls (hash algorithm, allocate urls among 1000 files, which is sure not to be duplicated between different files) there are 10,000 arrays, each array has 1000 integers, each array is in descending order, find the largest N number, N<1000
113. The underlying implementation of LinkedHashmap
114. The use of the version number of a class when serializing a class. If no version number is specified, how does the system handle it? What happens if you add a field?
115. What is the difference between Override and Overload
116. How did Java reflection work for one to five years