如果下半輩子只想 DEBUG 怎麼辦？

Transcript

1. 如果下半輩⼦子， 只想 DEBUG， 怎麼辦？ kudo@csie.io
2. https://www.flickr.com/photos/kwarz/13974382668 Welcome to Software Generation
3. BUG BUG BUG BUG BUG BUG BUG BUG BUG BUG BUG BUG BUG BUG BUG BUG BUG BUG BUG BUG BUG BUG BUG BUG BUG BUG BUG BUG BUG BUG BUG BUG BUG BUG BUG BUG BUG BUG BUG BUG BUG BUG BUG BUG BUG https://www.flickr.com/photos/djjohnson/169497259
4. DEBUG 也能出頭天的⼈人⽣生故事 • 中正資⼯工系 2002 - 2006 • 中正資⼯工所 2006 - 2008 (GAIS Lab) • CNA 記得當年 我只是個⼩小魯蛇
5. DEBUG 也能出頭天的⼈人⽣生故事 • Trend Micro 2008 - 2012 剛進公司的第⼀一年 you know 菜⿃鳥就是 DEBUG 命
6. DEBUG 也能出頭天的⼈人⽣生故事 • Trend Micro 2008 - 2012 第⼆二年 繼續 DEBUG
7. DEBUG 也能出頭天的⼈人⽣生故事 • Trend Micro 2008 - 2012 第三年 專職 DEBUG
8. DEBUG 也能出頭天的⼈人⽣生故事 • Trend Micro 2008 - 2012 然後 不⼩小⼼心就升了
9. DEBUG 也能出頭天的⼈人⽣生故事 • Trend Micro 2008 - 2012 專解⼈人所不能解的 BUG 這也是⼀一種價值
10. DEBUG 也能出頭天的⼈人⽣生故事 • Waveface 2012 - 2013 砍掉重練第⼀一年 you know 菜⿃鳥還是 DEBUG 命
11. DEBUG 也能出頭天的⼈人⽣生故事 • biideal 2013 - now • 從 software debugging 到
 product market debugging https://www.flickr.com/photos/gagillphoto/3336353424
12. 想法 驗證 學習
13. https://www.flickr.com/photos/photobunny_earl/993311118 抽絲剝繭
14. https://www.flickr.com/photos/plasticrevolver/164351244 找找看， 我的故事 有沒有 BUG ?
15. 開始吧 以 UNIX C 與JavaScript (Chrome DevTool) 為例
16. 你我都會的 DEBUG • printf() • fprintf() • 合理質疑，log 也是會掉的 • stdout is line buffered • stderr is unbuffered • FILE is fully buffered • In default C
17. 你我都會的 DEBUG • Logging 本⾝身是⼀一⾨門藝術 • multi-threaded • multi-processes • throughput C 講古時間 AXXP
18. 你我都會的 DEBUG • console.log() • console.error() • console.warn() • console.trace() • https://developer.chrome.com/devtools/docs/console-api Chrom e
19. Basic Debugger • gcc(clang) -g main.c • gdb(lldb) a.out • br • info locals • n / s / finish / cont • bt C
20. Basic Debugger Chrom e
21. Basic Debugger • Crash / Exception 相對是容易 抓的 bug • Debugger 黏上去就對了 https://www.flickr.com/photos/rachaelvoorhees/828354236
22. Conditional Breakpoint • br funcName if val == n • Sometimes, Conditional Breakpoint is slow • Do logic in code and set breakpoint at the block
23. Conditional Breakpoint C for (int num = 0; num < 100; ++num) { int randVal = rand() % 10; if (randVal == 0) { puts("set breakpoint here."); // raise(SIGINT); } printf("Result: %d\n”, num / randVal); }
24. Conditional Breakpoint Chrom e function foo() { var num, randVal; for (num = 0; num < 100; ++num) { randVal = Math.floor(Math.random() * 10); if (randVal == 0) { debugger; } console.log("Result: " + num / randVal); } }
25. Attach process • for Daemon / Service • gdb program pid C
26. Post-mortem Debugging • Onsite debug • Code sign / Build concern • Debug old product version https://www.flickr.com/photos/x1klima/14594615831
27. RELEASE vs DEBUG build • RELEASE vs DEBUG build • gcc -O + strip vs gcc -g • debug information(symbol) • symbol names / line number … etc • pdb / dSYM
28. 程式設計師的⾃自我 修養－連結、載⼊入、 程式庫 俞甲⼦子、⽯石凡、潘愛⺠民
29. Post-mortem Debugging • Linux as example • gdb executable_with_symbol • https://sourceware.org/gdb/onlinedocs/gdb/ Separate-Debug-Files.html C
30. Post-mortem Debugging • JavaScript as dynamic language • Best practice is to do compress • UglifyJS2, Google Closure Compiler • Source Map Chrom e
31. Post-mortem Debugging Chrom e function foo() { var num, randVal; for (num = 0; num < 100; ++num) { randVal = Math.floor(Math.random() * 10); if (randVal == 0) { debugger; } console.log("Result: " + num / randVal); } } function foo(){var o,a;for(o=0;100>o;++o)a=Math.floor(10*Math.random()),console.log("Result: "+o/a)}
32. Post-mortem Debugging • //# sourceMappingURL=main.min.js.map • Comment in minified JS file Chrom e {"version":3,"file":"main.min.js","sources":["main.c"],"names": ["foo","num","randVal","Math","floor","random","console","log"],"mappings":"AAAA,QAASA,OACP,G AAIC,GAAKC,CAET,KAAKD,EAAM,EAAS,IAANA,IAAaA,EACzBC,EAAUC,KAAKC,MAAsB,GAAhBD,KAAKE,UAI1BC,QAAQ C,IAAI,WAAaN,EAAMC"}
33. Debug Hanging C for (int num = 0; num < 100; ++num) { int randVal = rand() % 10; if (randVal == 0) { sleep(3000); } else { sleep(randVal); } }
34. Debug Hanging • run in debugger • Ctrl-C • bt C
35. Debug Hanging • run as you did • Get the pid • ulimit -c unlimited • kill -SIGTRAP [pid] • gdb execfile core • bt C • Use cases • Daemon / Service • PhantomJS hanging case
36. Memory Leak • valgrind • #define new DEBUG_NEW • http://stackoverflow.com/a/28447070 C
37. Memory Leak • JavaScript memory profiling 真是⼀一⾨門學問 • https://developer.chrome.com/devtools/docs/ javascript-memory-profiling Chrom e
38. Profiling • gprof • valgrind C http://mdkey.org/?p=174
39. Profiling • How to debug for a HTTP response timeout issue • framework / database / external call … etc W eb 想法 驗證 學習
40. Profiling W eb
41. Tools https://www.flickr.com/photos/zzpza/3269784239/
42. Mobile • Device mode • Device emulation • Network emulation • Media queries support Chrom e
43. Mobile Remote Debugging • Real device debugging • Mobile Safari • Chrome on Android Chrom e Safari https://developer.chrome.com/devtools/docs/remote-debugging
44. Inspect Network Traffic • WireShark http://linux.softpedia.com/get/Internet/HTTP-WWW-/Ethereal-1961.shtml
45. Inspect Network Traffic • Fiddler2 • HTTPS inspect
46. Inspect Network Traffic • mitmproxy • HTTPS inspect • Modification • Replay https://mitmproxy.org/
47. Error Tracking SaaS Sentry
48. Error Tracking SaaS Twitter Fabric Crashlytics Kit
49. Monitor / Profiling SaaS NewRelic http://newrelic.com/server-monitoring
50. Monitor / Profiling SaaS NewRelic
51. The Mind Set
52. • Server DEBUG • 讓它噴 • Fast Deployment • Client DEBUG • 盡其所能地防⽌止 Crash 並留下 log • Slow Upgrade
53. 恰到好處
54. https://www.flickr.com/photos/nicdalic/384854457 Give a hand
55. Testing
56. Dependency add(3, 6) == 9 calc(3, 6, adder) == 9 calc(3, 6, API) == 9
57. Dependency Unit Tests with dependencies are not CI friendly https://www.flickr.com/photos/jacobgarcia/2550146
58. Dependency Injection int adder(int a, int b) { return a + b; } int calc(int a, int b) { return adder(a, b); } int main(int argc, char *argv[]) { int result = calc(3, 6); printf("Result: %d\n", result); return EXIT_SUCCESS; }
59. int adder(int a, int b) { return a + b; } int calc(int a, int b, int (*strategy)(int, int)) { return (*strategy)(a, b); } int main(int argc, char *argv[]) { int result = calc(3, 6, &adder); printf("Result: %d\n", result); return EXIT_SUCCESS; }
60. int realRemoteAdder(int a, int b) { // Assume to get data from remote server sleep(10); return a + b; } int mockAdder(int a, int b) { return a + b; } int calc(int a, int b, int (*strategy)(int, int)) { return (*strategy)(a, b); } int main(int argc, char *argv[]) { int result = calc(3, 6, &mockAdder); printf("Result: %d\n", result); return EXIT_SUCCESS; }
61. Dependency Injection Framework • Google Fruit • Dagger • …
62. Mock Framework https://code.google.com/p/googlemock/wiki/CheatSheet#Using_Mocks_in_Tests
63. Mock Frameworks • Google C++ Mocking Framework • cmocka • Sinon.JS • ….
64. TDD / BDD 談好 interfaces
65. RECAP
66. 想法 驗證 學習
67. 恰到好處
68. References • http://debug.csie.io/ • Sample code • Slide downloads (TBD) • Issues & PR please