TL;DR

Turn your software inside out. The tool records everything you app does, and you then can analyze the execution flow. Bytecode instrumentation is handled by byte-buddy, UI is built on JavaFX.

Here is a basic example. We have a transactional method service and Hibernate is used as a JPA provider.

```
@Service
@Transactional
public class PersonStoreService {
    @Autowired
    private PersonRepository repository;

    public void save(Person person) {
        repository.save(person);
    }
}
```

Calling this method with ulyp agent enabled is able to provide a full call tree. No code change is required.

Blog posts

The underlying rationale for the development, technical design, as well as some use cases are outlined in the following blog posts:

• Ulyp: Recording Java code execution for faster debugging (ENG)
• Reverse engineer Spring Web in 5 minutes using a recording debugger (ENG)

How to use

Usage is relatively simple.

• First, download or build the agent

• Second, use VM properties in order to enable the recording. Here is the minimum set of options one will need for recording.

  -javaagent:/path/to/ulyp-agent-1.0.0.jar
  -Dulyp.methods=**.HibernateShowcase.*
  -Dulyp.file=/tmp/recording.dat
  

Recording starts when any method of a class which has class name HibernateShowcase is called. The data is written to the specified file which can later be opened in the UI.

Examples of method matchers are:

Matcher	Explanation
org.springframework.**.Service.*	Record any method of class Service in package org.springframework (or nested) package
**.Runnable.run	Record all Runnable instances
*.*	Record all calls (Experimental)

Options

The agent is controlled via JVM system properties.

Property	Description	Example	Default
ulyp.file	A path to a file where all recording data should be written	-Dulyp.file=/tmp/test.dat	-
ulyp.methods	A list of method matchers where recording should start	-Dulyp.methods=**.Runnable.run	Main method
ulyp.start	Controls when recording can start. default is start recording any time when some of ulyp.method is called. Another option is delay:X where X is the number of seconds to wait from the app launch, api - remote enable/disable (WIP)	-Dulyp.start=delay:120	default
ulyp.packages	A list of packages to instrument	-Dulyp.packages=org.springframework,io.grpc	All packages
ulyp.record-timestamps	Record duration of calls	-Dulyp.record-timestamps	Disabled
ulyp.exclude-packages	A list of packages to exclude from instrumentation	-Dulyp.exclude-packages=org.springframework	-
ulyp.exclude-types	A list of type matchers to exclude from instrumentation	-Dulyp.exclude-types=org.springframework.**.Interceptor	-
ulyp.record-constructors	Enables instrumentation (and possibly recording) of constructors	-Dulyp.record-constructors	Disabled
ulyp.record-collections	Records values (some number of items) of collections. Possible values are: NONE, JDK (only JDK collections), ALL (dangerous)	-Dulyp.record-collections=JDK	NONE
ulyp.record-collections.max-items	Max items of collections to record	-Dulyp.record-collections.max-items=5	3
ulyp.record-arrays	Records values (some number of items) of arrays	-Dulyp.record-arrays	Disabled
ulyp.record-arrays.max-items	Max items of arrays to record	-Dulyp.record-arrays.max-items=10	3
ulyp.record-lambdas	Enabled instrumentation (and possibly recording) of lambdas (experimental)	-Dulyp.record-lambdas	Disabled
ulyp.record-static-blocks	Enabled instrumentation (and possibly recording) of static blocks (experimental)	-Dulyp.record-static-blocks	Disabled
ulyp.print-types	A list of type matchers to print with toString() while recording their values	-Dulyp.print-types=com.enterprise.**.SomeEntity	-
ulyp.recorder.max-string-length	A maximum number of characters for String recording	-Dulyp.recorder.max-string-length=400	200

UI

Controls

Hotkey	Action
Hold Shift	Show full type names
Hold X	Show method call duration (if enabled with -Dulyp.record-timestamps while recording)
Press =	Increase font size
Press -	Decrease font size

Build from source

Build agent (no tests): ./gradlew :ulyp-agent:shadowJar

Build UI jar file (Java 11+ (preferred) or Java 8 Oracle with Java FX bundled) : ./gradlew :ulyp-ui:fatJar

UI jar file for a particular platform can be built as follows: ./gradlew :ulyp-ui:fatJar -Pplatform=mac

Available platforms for the build are: linux, linux-aarch64, win, mac, mac-aarch64