Periodic exporting MetricReader not working

Environment:

Symfony 5.4 with OpenTelemetry auto-instrumentation
PHP-FPM with configurable worker count (runing several pods in kubernetes)
Grafana Alloy as OTLP collector
http.server.request.duration histogram metric with semantic conventions

Steps to reproduce
POC is in repo: https://github.com/remunda/php-fpm-otel-poc
run ./k3drun.sh to deploy the whole app in local k8s cluster in docker with alloy (extended otel collector)

• set OTEL_METRIC_EXPORT_INTERVAL=60000
• run PHP with autoloaded OTEL PHP SDK
• obtain meter from cachedInstrumentation (or globals)
• create cumulative histogram
• record timing of every request in histogram
• get OTLP messages (eg. port-forward to grafana alloy and livedebug on otel receiver)

What is the expected behavior?

• metrics are exported every 60s

What is the actual behavior?

• metrics are exported after every HTTP Request (sample data of 1 push bellow)

Additional context
It looks like its not implementet at all, there is some TODO :-/ https://github.com/open-telemetry/opentelemetry-php/blob/main/src/Contrib/Otlp/MetricExporterFactory.php#L47 But I'm new in this codebase.

Although its marked in compatibility matrix as supported https://github.com/open-telemetry/opentelemetry-specification/blob/main/spec-compliance-matrix.md

Maybe I'm missing something, but I've spent on this issues tens of hours wondering whats going on and honestly I'm without ideas :D. I've tried to aggregate histograms on alloy but it broke my cluster how it spiked on CPU/RAM. On this site is decent load.

I will be wery thankful for any advice.
Is there for example another way to aggregate histogram metrics in process and push them according to the interval specifications?

----OTLP sample----
StartTimestamp: 2026-02-09 21:33:20.479847024 +0000 UTC
Timestamp: 2026-02-09 21:33:20.525514411 +0000 UTC
Count: 1
Sum: 0.044489
Min: 0.044489
Max: 0.044489
ExplicitBounds #0: 0.000000
ExplicitBounds #1: 5.000000
ExplicitBounds #2: 10.000000
ExplicitBounds #3: 25.000000
ExplicitBounds #4: 50.000000
ExplicitBounds #5: 75.000000
ExplicitBounds #6: 100.000000
ExplicitBounds #7: 250.000000
ExplicitBounds #8: 500.000000
ExplicitBounds #9: 1000.000000
Buckets #0, Count: 0
Buckets #1, Count: 1
Buckets #2, Count: 0
Buckets #3, Count: 0
Buckets #4, Count: 0
Buckets #5, Count: 0
Buckets #6, Count: 0
Buckets #7, Count: 0
Buckets #8, Count: 0
Buckets #9, Count: 0
Buckets #10, Count: 0
Exemplars:
Exemplar #0
     -> Trace ID: f7d3edf99d26e69921aa3b1c49e464ca
     -> Span ID: 936cb76028d1c8da
     -> Timestamp: 2026-02-09 21:33:20.524447749 +0000 UTC
     -> Value: 0.044489
ResourceMetrics #0
Resource SchemaURL: https://opentelemetry.io/schemas/1.38.0
Resource attributes:
     -> service.name: Str(oteltest-web)
     -> host.name: Str(php-app-5c8d5f9f8f-nh9cv)
     -> host.arch: Str(x86_64)
     -> os.type: Str(linux)
     -> os.description: Str(6.6.87.2-microsoft-standard-WSL2)
     -> os.name: Str(Linux)
     -> os.version: Str(#1 SMP PREEMPT_DYNAMIC Thu Jun  5 18:30:46 UTC 2025)
     -> process.runtime.name: Str(fpm-fcgi)
     -> process.runtime.version: Str(8.3.23)
     -> process.pid: Int(8)
     -> process.executable.path: Str(/usr/local/sbin/php-fpm)
     -> process.owner: Str(www-data)
     -> telemetry.sdk.name: Str(opentelemetry)
     -> telemetry.sdk.language: Str(php)
     -> telemetry.sdk.version: Str(1.12.0)
     -> telemetry.distro.name: Str(opentelemetry-php-instrumentation)
     -> telemetry.distro.version: Str(1.2.1)
ScopeMetrics #0
ScopeMetrics SchemaURL: 
InstrumentationScope oteltest-http 
Metric #0
Descriptor:
     -> Name: http.server.request.duration
     -> Description: Duration of HTTP server requests
     -> Unit: s
     -> DataType: Histogram
     -> AggregationTemporality: Cumulative
HistogramDataPoints #0
Data point attributes:
     -> http.request.method: Str(GET)
     -> http.response.status_code: Int(200)
     -> url.scheme: Str(http)
     -> network.protocol.version: Str(HTTP/1.1)
     -> http.route: Str(api_test)
--------

Thank you!

Start with src/Contrib/Otlp/MetricExporterFactory.php at the TODO referenced in the issue, then reproduce the behavior using ./k3drun.sh in the linked PHP-FPM proof of concept. Compare OTLP output with OTEL_METRIC_EXPORT_INTERVAL=60000; done means metrics are exported on the configured interval rather than after every HTTP request.