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Automatically start stracing process upon invocation

For a SystemTap script, how do I make sure I catch the fact a process is ending?How to show the totall amount of process ,main memory, virtual memory usage in SYSTEMTAP?In systemtap, how do I trap the return of a function in a user space process?systemtap remote debug user process with source codesystemtap:while resolving probe point: identifier 'process' at source: probe process().function no matchsystemtap: nothing for “sudo stap -L 'process(”/data1/nginx/sbin/nginx“).function(”*")'SystemTap Inter process communicationGet new pid from nd_syscall.vfork.return in systemtapsystemtap Child process exited with statusDetermine syscalls or subsystems a process is spending time waiting in

0

The intention of below SystemTap script is to start straceing whenever a process with a given filename is started.

It is called with the following command:

stap -g -v './sstrace.stp' "$PATTERN"

Where PATTERN can for example be mount.

#!/usr/bin/env stap

# Assign command line parameter to the variable.
@define target_filename %( @1 %) # The regex the script will trigger on given as CLI parameter

probe begin 
 printf( "Probe starting ...n" )
 printf( "Try to attach strace upon executing binary (regex) /%s/nn" , @target_filename )


probe end 
 printf( "Wrapping up ...n" )


probe syscall.execve 
 if ( filename =~ @target_filename ) 
 start_trace( pid() )
 


###
### FUNCTIONS
###

function start_trace( pid ) 
 raise( 19 )
 # Sleeping is bad practice in SystemTap probe, but don't know how to otherwise
 # wait for strace to initialize in time. This will not work as expected when
 # workting interactively. Compare these two results while increasing below sleep
 # to 1 second.
 # $ sudo ./go date
 # $ date; echo hi
 # $ bash -c 'date; echo hi'
 system( sprintf( "strace -f -p %i & sleep 0.01; kill -CONT %i" , pid , pid ) )

The idea is that I stop execution (raise( -19 )) of the target process long enough for strace to attach to the process and, then restarting the target process (kill -CONT $TARGET_PID). This often works.

Now the problem I really at least want to understand and hopefully solve, is the fact that on some systems I cannot kill -STOP the target process, it simply throws an error along the lines of: kill: process xyz does not. exist.

I know by the time the execve syscall is called, the PID already exists. What I don't understand is why it doesn't seem to obey the SIGSTOP.

Does anyone know why this happens, how to fix the SystemTap script or have an even smarter way to accomplish the goal starting to trace a process on the fly?

systemtap

share|improve this question

asked yesterday

jippiejippie

50751228

migrated from unix.stackexchange.com 4 hours ago

This question came from our site for users of Linux, FreeBSD and other Un*x-like operating systems.

add a comment | 

0

The intention of below SystemTap script is to start straceing whenever a process with a given filename is started.

It is called with the following command:

stap -g -v './sstrace.stp' "$PATTERN"

Where PATTERN can for example be mount.

#!/usr/bin/env stap

# Assign command line parameter to the variable.
@define target_filename %( @1 %) # The regex the script will trigger on given as CLI parameter

probe begin 
 printf( "Probe starting ...n" )
 printf( "Try to attach strace upon executing binary (regex) /%s/nn" , @target_filename )


probe end 
 printf( "Wrapping up ...n" )


probe syscall.execve 
 if ( filename =~ @target_filename ) 
 start_trace( pid() )
 


###
### FUNCTIONS
###

function start_trace( pid ) 
 raise( 19 )
 # Sleeping is bad practice in SystemTap probe, but don't know how to otherwise
 # wait for strace to initialize in time. This will not work as expected when
 # workting interactively. Compare these two results while increasing below sleep
 # to 1 second.
 # $ sudo ./go date
 # $ date; echo hi
 # $ bash -c 'date; echo hi'
 system( sprintf( "strace -f -p %i & sleep 0.01; kill -CONT %i" , pid , pid ) )

The idea is that I stop execution (raise( -19 )) of the target process long enough for strace to attach to the process and, then restarting the target process (kill -CONT $TARGET_PID). This often works.

Now the problem I really at least want to understand and hopefully solve, is the fact that on some systems I cannot kill -STOP the target process, it simply throws an error along the lines of: kill: process xyz does not. exist.

I know by the time the execve syscall is called, the PID already exists. What I don't understand is why it doesn't seem to obey the SIGSTOP.

Does anyone know why this happens, how to fix the SystemTap script or have an even smarter way to accomplish the goal starting to trace a process on the fly?

systemtap

share|improve this question

asked yesterday

jippiejippie

50751228

migrated from unix.stackexchange.com 4 hours ago

This question came from our site for users of Linux, FreeBSD and other Un*x-like operating systems.

add a comment | 

The intention of below SystemTap script is to start straceing whenever a process with a given filename is started.

It is called with the following command:

stap -g -v './sstrace.stp' "$PATTERN"

Where PATTERN can for example be mount.

#!/usr/bin/env stap

# Assign command line parameter to the variable.
@define target_filename %( @1 %) # The regex the script will trigger on given as CLI parameter

probe begin 
 printf( "Probe starting ...n" )
 printf( "Try to attach strace upon executing binary (regex) /%s/nn" , @target_filename )


probe end 
 printf( "Wrapping up ...n" )


probe syscall.execve 
 if ( filename =~ @target_filename ) 
 start_trace( pid() )
 


###
### FUNCTIONS
###

function start_trace( pid ) 
 raise( 19 )
 # Sleeping is bad practice in SystemTap probe, but don't know how to otherwise
 # wait for strace to initialize in time. This will not work as expected when
 # workting interactively. Compare these two results while increasing below sleep
 # to 1 second.
 # $ sudo ./go date
 # $ date; echo hi
 # $ bash -c 'date; echo hi'
 system( sprintf( "strace -f -p %i & sleep 0.01; kill -CONT %i" , pid , pid ) )

The idea is that I stop execution (raise( -19 )) of the target process long enough for strace to attach to the process and, then restarting the target process (kill -CONT $TARGET_PID). This often works.

Now the problem I really at least want to understand and hopefully solve, is the fact that on some systems I cannot kill -STOP the target process, it simply throws an error along the lines of: kill: process xyz does not. exist.

I know by the time the execve syscall is called, the PID already exists. What I don't understand is why it doesn't seem to obey the SIGSTOP.

Does anyone know why this happens, how to fix the SystemTap script or have an even smarter way to accomplish the goal starting to trace a process on the fly?

systemtap

share|improve this question

asked yesterday

jippiejippie

50751228

stap -g -v './sstrace.stp' "$PATTERN"

#!/usr/bin/env stap

# Assign command line parameter to the variable.
@define target_filename %( @1 %) # The regex the script will trigger on given as CLI parameter

probe begin 
 printf( "Probe starting ...n" )
 printf( "Try to attach strace upon executing binary (regex) /%s/nn" , @target_filename )


probe end 
 printf( "Wrapping up ...n" )


probe syscall.execve 
 if ( filename =~ @target_filename ) 
 start_trace( pid() )
 


###
### FUNCTIONS
###

function start_trace( pid ) 
 raise( 19 )
 # Sleeping is bad practice in SystemTap probe, but don't know how to otherwise
 # wait for strace to initialize in time. This will not work as expected when
 # workting interactively. Compare these two results while increasing below sleep
 # to 1 second.
 # $ sudo ./go date
 # $ date; echo hi
 # $ bash -c 'date; echo hi'
 system( sprintf( "strace -f -p %i & sleep 0.01; kill -CONT %i" , pid , pid ) )

share|improve this question

asked yesterday

jippiejippie

50751228

share|improve this question

asked yesterday

jippiejippie

50751228

asked yesterday

jippiejippie

50751228

asked yesterday

jippiejippie

50751228