uflow(8)

NAME
uflow - Print a flow graph of method calls in high-level languages.

SYNOPSIS
uflow [-h] [-M METHOD] [-C CLAZZ] [-v] {java,python,ruby} pid

DESCRIPTION
uflow traces method calls and prints them in a flow graph that can facilitate 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 Node, Java, Python, and Ruby. 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:+ExtendedDTraceProbes" is required. 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/ClassName" to refer to classes.

-v  Print the resulting BPF program, for debugging purposes.

{java,python,ruby}
    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 collection mechanism. Do not use for performance- sensitive production scenarios, 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)