Which of the following are valid .NET CLR JIT performance counters? 1) Total memory used for JIT compilation 2) Average memory used for JIT compilation 3) Number of methods that failed to compile with the standard JIT 4) Percentage of processor time spent performing JIT compilation 5) Percentage of memory currently dedicated for JIT compilation

Introduction / Context:
Just-In-Time (JIT) performance counters in the .NET CLR help developers measure JIT compilation activity. Knowing which counters actually exist prevents misinterpretation of performance data.

Given Data / Assumptions:

• The question lists five candidate counters.
• We must identify real counters exposed by the .NET CLR JIT category.

Concept / Approach:
The CLR JIT category includes counters such as Standard JIT Failures (methods that failed to compile) and Time in JIT (%) (percentage of processor time spent in JIT). Memory-usage counters like “Total memory used by JIT” are not standard JIT counters.

Step-by-Step Solution:

Verification / Alternative check:
Cross-checking typical Performance Monitor categories for .NET CLR JIT confirms the presence of “Time in JIT (%)” and “Standard JIT Failures”.

Why Other Options Are Wrong:

• 1, 5: Memory-specific counters are not part of the JIT category.
• 1, 2: Both are nonstandard memory counters.
• 4, 5: Includes a non-existent memory counter.
• None of these: Incorrect because 3 and 4 are valid.

Common Pitfalls:
Confusing JIT counters with GC or process memory counters.

Final Answer:
3, 4