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  Use DTrace to diagnose gdb issues

A few days ago, I installed the newest 64-bit gdb program (version 7.7.1) on Solaris 10 (X86_64 platform) to debug programs. After playing with the gdb a day, I found 2 issues about gdb:(1) The "set follow-fork-mode child" command doesn't take effect. By default, after the parent process forks the child process, the gdb will track the parent process, so this command can make gdb begin to follow the child process. But this command works OK on Linux.(2) The gdb can't parse the 32-bit application c...

   DTrace, debug, gdb, UNIX     2014-06-28 05:11:20

  When will resizing be triggered in Java HashMap?

HashMap is one of the most frequently used collection types in Java, it stores key-value pairs. Ideally it expects to use hash table which expects the data access time complexity to be O(1), however, due to hash conflicts, in reality, it uses linked list or red-black tree to store data which makes the worst case time complexity to be O(logn).  Although collections are using data structures like arrays and linked lists, unlike arrays, they will dynamically resize when there is not enough spa...

   JAVA,RESIZE,HASHMAP,THRESHOLD     2020-05-02 20:41:19

  WireGuard VPN Troubleshooting

When you are working as a network/cluster admin for you team to config the WireGuard VPN for other members, you may meet some of the problems below and these are the solution you can try to fix them. ----------------------------------------------------------------------------------------------------------- Problem [1]: The WireGuard handshake request send from the client can be received from the server but the server's response was blocked at some where so the client can not receive serv...

   WIREGUARD,VPN,TROUBLESHOOTING     2021-12-14 09:17:46

  First Touch on OpenAI API

It’s been a while since ChatGPT launched, and I’ve been meaning to try out the OpenAI API. Recently, I finally took the plunge, so here’s a walkthrough of my initial experience using it. Objective: I’ve previously used ChatGPT’s interface for language translation tasks between Chinese and English. For this API experiment, I aimed to set up a simple translation function using the OpenAI API. Step 1: Getting the API Key First, to access the API, I created an OpenAI ac...

   TUTORIAL,API,TRANSLATION,OPENAI,FREE ACCOUNT     2024-11-11 22:25:07

  How to make select in WinSock exceed the 64-socket limit

When doing cross-platform network programming, the only API available on Windows that corresponds to the epoll/kevent style reactor event model is select. However, it has a limitation: the number of sockets passed into select cannot exceed FD_SETSIZE, which is set to 64. Therefore, select in Java’s NIO on Windows also has the same limit. Many services ported to Windows that use the reactor model face this constraint, which often gives the impression that server programs on Windows hav...

   EXCEED,SELECT,JAVA,WINDOWS     2024-10-31 23:47:50

  Exit main thread and keep other threads running in C

In C programming, if using return in main function, the whole process will terminate. To only let main thread gone, and keep other threads live, you can use thrd_exit in main function. Check following code: #include #include #include int print_thread(void *s) { thrd_detach(thrd_current()); for (size_t i = 0; i < 5; i++) { sleep(1); printf("i=%zu\n", i); } thrd_exit(0); } int main(void) { ...

   C LANGUAGE,MULITHREAD,MAIN THREAD     2020-08-14 21:20:04

  Add ContextMenu to a customized View in Android

In Android, we may sometimes need to add ContextMenu to a View, it's not so easy to add ContextMenu to a customized View. Here we explain how to add ContextMenu to a customized View. First, we may need to create View.OnCreateContextMenuListener so that the customized view can register for it. Here is the class definition: public class GraphView extends View {     private View.OnCreateContextMenuListener vC = new View.OnCreateContextMenuListener() {       &...

   Android, ContextMenu,Customized view     2012-11-04 07:10:40

  An experience of fixing a memory-corruption bug

During the last 4 months, I was disturbed by a memory-corruption bug, and this bug will cause program crash. Until last Monday, I found the root cause and fixed it. This debug process is a difficult but memorable experience, so I will share it in this article.   My program works as a SMS Hub. When it receives a SMS, it will allocate a structure in heap memory like this: typedef struct { ...... int *a[8]; ...... } info; After processing the SMS, the program will free the m...

   c, debug, unix, solaris, multi-thread     2014-05-04 03:52:43

  Do you really understand C? 21st International Obfuscated C Code Contest winning entries

The 21st International Obfuscated C Code Contest(IOCCC) officially launched the winning source code. IOCCC requires contestants to write the most creative and the most obfuscated C codes with the size limited to 4kb and less Work of each participant is impressive. The winners, including one French, one Korean, five Americans, one Belgian, one Israeli, one British, four Japanese and one Chinese. Here we list some codes: Best short program Seonghoon Kang  from Korea- Decodes spelled out ...

   C,Obsfucation contest     2012-10-25 12:26:55

  All I Know About Certificates -- Clients

 Finally, in last article we’ve covered the responsibilities of CAs, showing that being a CA isn’t simple and has high management costs, explaining why issuing certificates costs money! This article we will cover the client in this chain. Verifying Certificates as a Client For clients, verifying certificates isn’t simple either. Articles introducing TLS handshakes often mention "the server sends back a certificate, and the client verifies it," but in reality, as ...

   CLIENTS,WEBSITES,SSL CERTIFICATE,CERTIFICATE AUTHORITY,CA     2024-07-26 22:24:30

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