uflow(8) System Manager's Manual uflow(8)
NAME
uflow, javaflow, perlflow, phpflow, pythonflow, rubyflow, tclflow -
Print a flow graph of method calls in high-level languages.
SYNOPSIS
javaflow [-h] [-M METHOD] [-C CLAZZ] [-v] pid
perlflow [-h] [-M METHOD] [-C CLAZZ] [-v] pid
phpflow [-h] [-M METHOD] [-C CLAZZ] [-v] pid
pythonflow [-h] [-M METHOD] [-C CLAZZ] [-v] pid
rubyflow [-h] [-M METHOD] [-C CLAZZ] [-v] pid
tclflow [-h] [-M METHOD] [-C CLAZZ] [-v] pid
uflow [-h] [-M METHOD] [-C CLAZZ] [-v] [-l
{java,perl,php,python,ruby,tcl}] pid
DESCRIPTION
uflow traces method calls and prints them in a flow graph that can fa-
cilitate debugging and diagnostics by following the program's execution
(method flow).
This tool relies on USDT probes embedded in many high-level languages,
such as Java, Perl, PHP, Python, Ruby, and Tcl. It requires a runtime
instrumented with these probes, which in some cases requires building
from source with a USDT-specific flag, such as "--enable-dtrace" or
"--with-dtrace". For Java processes, the startup flag "-XX:+Extended-
DTraceProbes" is required. For PHP processes, the environment variable
USE_ZEND_DTRACE must be set to 1.
Since this uses BPF, only the root user can use this tool.
REQUIREMENTS
CONFIG_BPF and bcc.
OPTIONS
-M METHOD
Print only method calls where the method name begins with this
string.
-C CLAZZ
Print only method calls where the class name begins with this
string. The class name interpretation strongly depends on the
language. For example, in Java use "package/subpackage/Class-
Name" to refer to classes.
-v Print the resulting BPF program, for debugging purposes.
{java,perl,php,python,ruby,tcl}
The language to trace.
pid The process id to trace.
EXAMPLES
Follow method flow in a Ruby process:
# uflow ruby 148
Follow method flow in a Java process where the class name is
java.lang.Thread:
# uflow -C java/lang/Thread java 1802
FIELDS
CPU The CPU number on which the method was invoked. This is useful
to easily see where the output skips to a different CPU.
PID The process id.
TID The thread id.
TIME The duration of the method call.
METHOD The method name.
OVERHEAD
This tool has extremely high overhead because it prints every method
call. For some scenarios, you might see lost samples in the output as
the tool is unable to keep up with the rate of data coming from the
kernel. Filtering by class or method prefix can help reduce the amount
of data printed, but there is still a very high overhead in the collec-
tion mechanism. Do not use for performance- sensitive production sce-
narios, and always test first.
SOURCE
This is from bcc.
https://github.com/iovisor/bcc
Also look in the bcc distribution for a companion _example.txt file
containing example usage, output, and commentary for this tool.
OS
Linux
STABILITY
Unstable - in development.
AUTHOR
Sasha Goldshtein
SEE ALSO
trace(8), ustat(8)
USER COMMANDS 2018-10-09 uflow(8)
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