End-to-End Tracing of Ajax/Java Applications Using DTrace

End-to-End Tracing of Ajax/Java Applications Using DTrace

Category: Utility

We posted about using DTrace to profile Firefox in the past, and

today Amit Hurvitz published a piece on Ajax, DTrace and Where They Meet.

 

JAVASCRIPT

 

1. #!/usr/sbin/dtrace -Zs
2.  
3. #pragma D option quiet
4. #pragma D option switchrate=10
5.  
6. dtrace:::BEGIN
7. {
8.         jsIndent = 0;
9.         jsFile = "ajax-validation";
10.         javaMethodBoundary= "doGet";
11.         startTimestamp = timestamp;
12. }
13.  
14. *mozilla$1:::js_function-entry
15. /basename(copyinstr(arg0)) == jsFile/
16. {
17.         jsIndent += 2;
18.         printf("%*s -> %s:%s (JavaScript)(elapsed ms: %d) ", jsIndent, "",
19.             jsFile, copyinstr(arg2), (timestamp - startTimestamp) / 1000);
20. }
21.  
22. *mozilla$1:::js_function-return
23. /basename(copyinstr(arg0)) == jsFile/
24. {
25.         printf("%*s < - %s:%s (JavaScript)(elapsed ms: %d) ", jsIndent, "",
26.             jsFile, copyinstr(arg2), (timestamp - startTimestamp) / 1000);
27.         jsIndent -= 2;
28. }
29.  
30.  
31. hotspot$2:::method-entry
32. {
33.         self->strPtr = (char *)copyin(arg1, args[2]+1);
34.         self->strPtr[(int)args[2]] = '';
35.         self->classStr = (string)self->strPtr;
36.         self->strPtr = (char *)copyin(arg3, (int)args[4]+1);
37.         self->strPtr[(int)args[4]] = '';
38.         self->methodStr = (string)self->strPtr;
39. }
40.  
41. hotspot$2:::method-entry
42. /javaMethodBoundary == self->methodStr/
43. {
44.         self->interested = 1;
45.         self->indent = 0;
46. }
47.  
48. hotspot$2:::method-entry
49. /self->interested/
50. {
51.         self->indent += 2;
52.         printf("%*s -> %s:%s (Java)(elapsed ms: %d) ", self->indent, "",
53.             self->classStr, self->methodStr, (timestamp - startTimestamp) / 1000);
54. }
55.  
56. hotspot$2:::method-return
57. {
58.         self->strPtr = (char *)copyin(arg1, args[2]+1);
59.         self->strPtr[(int)args[2]] = '';
60.         self->classStr = (string)self->strPtr;
61.         self->strPtr = (char *)copyin(arg3, (int)args[4]+1);
62.         self->strPtr[(int)args[4]] = '';
63.         self->methodStr = (string)self->strPtr;
64. }
65.  
66. hotspot$2:::method-return
67. /self->interested/
68. {
69.         printf("%*s < - %s:%s (Java)(elapsed ms: %d) ", self->indent, "",
70.             self->classStr, self->methodStr, (timestamp - startTimestamp) / 1000);
71.         self->indent -= 2;
72. }
73.  
74. hotspot$2:::method-return
75. /javaMethodBoundary == self->methodStr/
76. {
77.         self->interested = 0;
78.         /* exit(0); */
79. }

It then continues to show timings of methods and such. This may not be the simplest solution for debugging, but at least you can get inside the black box when you need too.