Metrics in EF Core

Entity Framework Core (EF Core) exposes continuous numeric metrics which can provide a good indication of your program's health. These metrics can be used for the following purposes:

• Track general database load in realtime as the application is running
• Expose problematic coding practices which can lead to degraded performance
• Track down and isolate anomalous program behavior

Metrics

EF Core reports metrics via the standard xref:System.Diagnostics.Metrics?displayProperty=nameWithType API. Microsoft.EntityFrameworkCore is the name of the meter. It's recommended to read .NET documentation on metrics.

[!NOTE] This feature was introduced in EF Core 9.0. See event counters below for older versions of EF Core.

Metrics and their meaning

• microsoft.entityframeworkcore.active_dbcontexts
• microsoft.entityframeworkcore.queries
• microsoft.entityframeworkcore.savechanges
• microsoft.entityframeworkcore.compiled_query_cache_hits
• microsoft.entityframeworkcore.compiled_query_cache_misses
• microsoft.entityframeworkcore.execution_strategy_operation_failures
• microsoft.entityframeworkcore.optimistic_concurrency_failures

Metric: microsoft.entityframeworkcore.active_dbcontexts

Available starting in: Entity Framework Core 9.0.

Metric: microsoft.entityframeworkcore.queries

Available starting in: Entity Framework Core 9.0.

Metric: microsoft.entityframeworkcore.savechanges

Available starting in: Entity Framework Core 9.0.

Metric: microsoft.entityframeworkcore.compiled_query_cache_hits

Available starting in: Entity Framework Core 9.0.

Metric: microsoft.entityframeworkcore.compiled_query_cache_misses

Available starting in: Entity Framework Core 9.0.

Metric: microsoft.entityframeworkcore.execution_strategy_operation_failures

Available starting in: Entity Framework Core 9.0.

Metric: microsoft.entityframeworkcore.optimistic_concurrency_failures

Available starting in: Entity Framework Core 9.0.

Event Counters (legacy)

EF Core reports metrics via the standard .NET event counters feature; it's recommended to read this blog post for a quick overview of how counters work.

Attach to a process using dotnet-counters

The dotnet-counters tool can be used to attach to a running process and report EF Core event counters regularly; nothing special needs to be done in the program for these counters to be available.

First, install the dotnet-counters tool: dotnet tool install --global dotnet-counters.

Next, find the process ID (PID) of the .NET process running your EF Core application:

Windows

1. Open the Windows Task Manager by right-clicking on the task bar and selecting "Task Manager".
2. Make sure that the "More details" option is selected at the bottom of the window.
3. In the Processes tab, right-click a column and make sure that the PID column is enabled.
4. Locate your application in the process list, and get its process ID from the PID column.

Linux or macOS

1. Use the ps command to list all processes running for your user.
2. Locate your application in the process list, and get its process ID from the PID column.

Inside your .NET application, the process ID is available as Process.GetCurrentProcess().Id; this can be useful for printing the PID upon startup.

Finally, launch dotnet-counters as follows:

dotnet counters monitor --counters Microsoft.EntityFrameworkCore -p <PID>

dotnet-counters will now attach to your running process and start reporting continuous counter data:

Press p to pause, r to resume, q to quit.
 Status: Running

[Microsoft.EntityFrameworkCore]
    Active DbContexts                                               1
    Execution Strategy Operation Failures (Count / 1 sec)           0
    Execution Strategy Operation Failures (Total)                   0
    Optimistic Concurrency Failures (Count / 1 sec)                 0
    Optimistic Concurrency Failures (Total)                         0
    Queries (Count / 1 sec)                                         1
    Queries (Total)                                               189
    Query Cache Hit Rate (%)                                      100
    SaveChanges (Count / 1 sec)                                     0
    SaveChanges (Total)                                             0

Counters and their meaning

Additional resources

• .NET documentation on event counters