[PDF] Debugging Tricks with Apache HTTP Server 24 PDF AC2014-Debug.pdf

7 avr 2014 · Tricks with Apache HTTP Server 2 4 otherwise included Apache HTTP Server lower-level [core:trace5] Request received from client: GET / HTTP/1 1 httpd hooks are what allow different modules to handle or otherwise

15 fév 2014 · In that case Apache skips to the logging phase (mod_perl executes all See the HTTP Request Handler Skeleton for a description of handler

[PDF] Debugging Tricks with Apache HTTP Server 24

[PDF] Apache Server Architecture

Apache is made to handle all of these requests Page 6 ▻ Multithreaded and Multi-processed Web Servers ▻ When an HTTP request arrives,

[PDF] Apache Pools - publishUP - Universität Potsdam

8 juil 2004 · Figure 2 2: Behavior of a simple HTTP server • full implementation of HTTP (all versions) • handling of concurrent requests (multiprocessing

[PDF] Architecture recovery of Apache 13 — A case study

World Wide Web (WWW) and the Apache HTTP Server The amined the Apache 1 3 HTTP server ing system calls for process handling (fork, exec), signals,

[PDF] Apache HTTP Server Documentation Version 25

1 jui 2016 · MOD REQUEST Provides Filters to handle and make available HTTP request bodies MOD REFLECTOR Provides Reflection of a request body

[PDF] Measurement, Analysis and Performance Improvement of the

HTTP “GET” commands to the Web server, requesting for files in the test file set Apache uses multiple processes to handle multiple requests concurrently

[PDF] Servers: Concurrency and Performance HTTP Server Inside your

HTTP Server • HTTP Server Handle request – GET /index html (Apache, Tomcat/Java, etc) Measures offered load response time throughput utilization

Debugging

Tricks with

Apache HTTP

Server 2.4

Je Trawick

Introduction

What kinds of

issues encountered

Using tools to

look inside the web server

Looking from

the outside

What if you

build the code dierently

Compare with

httpd 2.2

References

and further readingDebugging Tricks with Apache HTTP Server 2.4

Je Trawick

http://emptyhammock.com/ trawick@emptyhammock.com

April 7, 2014

Debugging

Tricks with

Apache HTTP

Server 2.4

Je Trawick

Introduction

What kinds of

issues encountered

Using tools to

look inside the web server

Looking from

the outside

What if you

build the code dierently

Compare with

httpd 2.2

References

and further readingGet these slides...

Debugging

Tricks with

Apache HTTP

Server 2.4

Je Trawick

Introduction

What kinds of

issues encountered

Using tools to

look inside the web server

Looking from

the outside

What if you

build the code dierently

Compare with

httpd 2.2

References

and further readingTable of Contents

1Introduction2What kinds of issues encountered3Using tools to look inside the web server4Looking from the outside5What if you build the code dierently6Compare with httpd 2.27References and further reading

Debugging

Tricks with

Apache HTTP

Server 2.4

Je Trawick

Introduction

What kinds of

issues encountered

Using tools to

look inside the web server

Looking from

the outside

What if you

build the code dierently

Compare with

httpd 2.2

References

and further readingIntroduction | Who am I?

I've worked at

several large corporations, for over two decades my own one-personcompany, Emptyhammock, for the last two yearsI've worked on several products which were primarily based on or otherwise included Apache HTTP Serverlower-level networking products web applications I've debuggedmanycustomer and user problems over the years.

Debugging

Tricks with

Apache HTTP

Server 2.4

Je Trawick

Introduction

What kinds of

issues encountered

Using tools to

look inside the web server

Looking from

the outside

What if you

build the code dierently

Compare with

httpd 2.2

References

and further readingIntroduction | What will we attempt to cover?

Touch on all the basics.

Describe all the new httpd 2.4 debugging features. Summarize the techniques which are dierent with httpd 2.2.

Debugging

Tricks with

Apache HTTP

Server 2.4

Je Trawick

Introduction

What kinds of

issues encountered

Using tools to

look inside the web server

Looking from

the outside

What if you

build the code dierently

Compare with

httpd 2.2

References

and further readingWhat kinds of issues encountered Crash

Hang of server

Stall of individual requests

Termination

Bad response time

Limited concurrency

without problem symptomsHigh CPU

High memory

High consumption of other

pooled resourcesIncorrect output - wrong transformationIncorrect output - missing/bad protocol element

Debugging

Tricks with

Apache HTTP

Server 2.4

Je Trawick

Introduction

What kinds of

issues encountered

Using tools to

look inside the web server

Looking from

the outside

What if you

build the code dierently

Compare with

httpd 2.2

References

and further readingNon-problems

Validate behavior of new software/conguration

Understand steady-state behavior for baseline when something is wrong

Debugging

Tricks with

Apache HTTP

Server 2.4

Je Trawick

Introduction

What kinds of

issues encountered

Using tools to

look inside the web server

Looking from

the outside

What if you

build the code dierently

Compare with

httpd 2.2

References

and further readingUsing tools to look inside the web server Logging (the information itself, the timestamp, information

about other processing at about the same time)OS-level tools (view use of resources, whether discrete

items like les or continuous like CPU)CPU-, code-level tools (determine what code is running frequently, what is running for the request, analyze memory references, walk through the processing of a request, etc.)

Debugging

Tricks with

Apache HTTP

Server 2.4

Je Trawick

Introduction

What kinds of

issues encountered

Using tools to

look inside the web server

Looking from

the outside

What if you

build the code dierently

Compare with

httpd 2.2

References

and further readingCareful with logging! As you increase the level of logging, you increase the chances that private data will be logged.Passwords, session keys, etc. Modules/log congurations of particular interest:moddumpio, modlogcong when congured to log certain request or response header eldsmodlogforensic http (the built-in module) when congured at higher trace levels

Debugging

Tricks with

Apache HTTP

Server 2.4

Je Trawick

Introduction

What kinds of

issues encountered

Using tools to

look inside the web server

Looking from

the outside

What if you

build the code dierently

Compare with

httpd 2.2

References

and further readingLogging

Error log

Debugging

Tricks with

Apache HTTP

Server 2.4

Je Trawick

Introduction

What kinds of

issues encountered

Using tools to

look inside the web server

Looking from

the outside

What if you

build the code dierently

Compare with

httpd 2.2

References

and further readingError log records

Congurable content

Fields dropped when information is unavailable

Third-party modules can implement their own elds

Typical message:

[Sun Oct 28 13:37:27.676386 2012] [:error] [pid 14340:tid 140625844377344] [client 127.0.0.1:50837] mod_wsgi (pid=14340): Target WSGI script /home/trawick/myhg/apache/documents/AC20

12EU/lookup.wsgi

does not contain WSGI application application

Debugging

Tricks with

Apache HTTP

Server 2.4

Je Trawick

Introduction

What kinds of

issues encountered

Using tools to

look inside the web server

Looking from

the outside

What if you

build the code dierently

Compare with

httpd 2.2

References

and further

readingHiding error log eldsThe ErrorLogFormat directive can limit which elds are logged, but you could implement post-processing

to remove elds as appropriate for what you are debugging.

My own silly mechanism:

$ grep Accept-Ranges logs/error_log

[Thu Apr 03 07:26:49.605322 2014] [http:trace4] [pid 13680:tid 140130244732672] http_filters.c(837): [client 192.168.1.207:60141] Accept-Ranges: bytes

$ grep Accept-Ranges logs/error_log | nots.pl

[http:trace4] [pid 13680:tid 140130244732672] http_filters.c(837): [client 192.168.1.207:60141] Accept-Ranges: bytes

$ grep Accept-Ranges logs/error_log | nots.pl | nomodlevel.pl

[pid 13680:tid 140130244732672] http_filters.c(837): [client 192.168.1.207:60141] Accept-Ranges: bytes

[PDF] [PDF] Debugging Tricks with Apache HTTP Server 24

Debugging

Tricks with

Apache HTTP

Server 2.4

Je Trawick

Introduction

What kinds of

Using tools to

Looking from

What if you

Compare with

References

Je Trawick

April 7, 2014

Debugging

Tricks with

Apache HTTP

Server 2.4

Je Trawick

Introduction

What kinds of

Using tools to

Looking from

What if you

Compare with

References

Debugging

Tricks with

Apache HTTP

Server 2.4

Je Trawick

Introduction

What kinds of

Using tools to

Looking from

What if you

Compare with

References

1Introduction2What kinds of issues encountered3Using tools to look inside the web server4Looking from the outside5What if you build the code dierently6Compare with httpd 2.27References and further reading

Debugging

Tricks with

Apache HTTP

Server 2.4

Je Trawick

Introduction

What kinds of

Using tools to

Looking from

What if you

Compare with

References

I've worked at

Debugging

Tricks with

Apache HTTP

Server 2.4

Je Trawick

Introduction

What kinds of

Using tools to

Looking from

What if you

Compare with

References

Touch on all the basics.

Debugging

Tricks with

Apache HTTP

Server 2.4

Je Trawick

Introduction

What kinds of

Using tools to

Looking from

What if you

Compare with

References

Hang of server

Stall of individual requests