Dependency detection: duplicated log entries, potentially duplicated invocations

[fallwith]

Issues:

• dependency detection logic is double reported for every instrumented gem
• dependency detection logic may possibly also be involving doubled, redundant invocations

To reproduce:

• set the log level to debug and init the agent
• observe the log to see duplicated detection lines such as these:

DEBUG : Using auto configuration value for bunny to configure instrumentation
DEBUG : Using auto configuration value for bunny to configure instrumentation
DEBUG : Using auto configuration value for concurrent_ruby to configure instrumentation
DEBUG : Using auto configuration value for concurrent_ruby to configure instrumentation
DEBUG : Using auto configuration value for curb to configure instrumentation
DEBUG : Using auto configuration value for curb to configure instrumentation
DEBUG : Using auto configuration value for delayed_job to configure instrumentation
DEBUG : Using auto configuration value for delayed_job to configure instrumentation

Source:
The log output is generated by the fetch_config_value method defined in lib/new_relic/dependency_detection.rb.

Pathways:
The doubled log output is produced by 2 different call stacks:

# pathway 1
"lib/new_relic/dependency_detection.rb:183:in `fetch_config_value'",
"lib/new_relic/dependency_detection.rb:202:in `config_value'",
"lib/new_relic/dependency_detection.rb:170:in `block (2 levels) in <class:Dependent>'",
"lib/new_relic/dependency_detection.rb:139:in `allowed_by_config?'",
"lib/new_relic/dependency_detection.rb:122:in `check_dependencies'",
"lib/new_relic/dependency_detection.rb:64:in `dependencies_satisfied?'",
"lib/new_relic/dependency_detection.rb:28:in `block in detect!'",
"lib/new_relic/dependency_detection.rb:27:in `each'",
"lib/new_relic/dependency_detection.rb:27:in `detect!'",
"lib/new_relic/control/instrumentation.rb:64:in `_install_instrumentation'",
"lib/new_relic/control/instrumentation.rb:47:in `install_instrumentation'",
"lib/new_relic/control/private_instance_methods.rb:39:in `init_instrumentation'",
"lib/new_relic/control/instance_methods.rb:75:in `init_plugin'",

# pathway 2
"lib/new_relic/dependency_detection.rb:183:in `fetch_config_value'",
"lib/new_relic/dependency_detection.rb:202:in `config_value'",
"lib/new_relic/dependency_detection.rb:170:in `block (2 levels) in <class:Dependent>'",
"lib/new_relic/dependency_detection.rb:31:in `block in detect!'",
"lib/new_relic/dependency_detection.rb:27:in `each'",
"lib/new_relic/dependency_detection.rb:27:in `detect!'",
"lib/new_relic/control/instrumentation.rb:64:in `_install_instrumentation'",
"lib/new_relic/control/instrumentation.rb:47:in `install_instrumentation'",
"lib/new_relic/control/private_instance_methods.rb:39:in `init_instrumentation'",
"lib/new_relic/control/instance_methods.rb:75:in `init_plugin'",

Impact:

• The agent logs more than it should when using a debug log level (default = info)
• The agent potentially does more detection work that it needs to at startup

[workato-integration]

https://new-relic.atlassian.net/browse/NR-250429

[kaylareopelle]

This one reminds me of #2434

[kaylareopelle]

I love the detailed repro and data in your description here

[fallwith]

Let's confirm the output shown in the description has gone away once #2434 has been completed.

[fallwith]

We'll let #2434 drive this one. Closing as a dupe.