Performance Tracking¶

Last updated 2 May 2023

The Store can record metrics on executed operations (e.g., get and put). Metric collection is disabled by default and can be enabled by passing metrics=True to a Store constructor.

Enabling Metrics¶

import dataclasses
from proxystore.connectors.file import FileConnector
from proxystore.store import register_store
from proxystore.store.base import Store

store = Store(
   name='example-store',
   connector=FileConnector('/tmp/proxystore-dump'),
   metrics=True,  # (1)!
)
register_store(store)
assert store.metrics is not None

Metric tracking is not enabled by default.

Metrics are accessed via the Store.metrics property. This property will be None when metrics are disabled.

Warning

Metrics are local to each Store instance. In multi-process applications or applications that instantiate multiple Store instances, Store.metrics will only represent a partial view of the overall performance.

Three types of metrics are collected.

Attributes: arbitrary attributes associated with an operation.
Counters: scalar counters that represent the number of times an event occurs.
Times: durations of events.

A Simple Example¶

Consider executing a get and put operation on store.

>>> key = store.put([0, 1, 2, 3, 4, 5])
>>> store.get(key)

We can inspect the metrics recorded for operations on key.

>>> metrics = store.metrics.get_metrics(key)

>>> tuple(field.name for field in dataclasses.fields(metrics))
('attributes', 'counters', 'times')

metrics is an instance of Metrics which is a dataclass with three fields: attributes, counters, and times. We can further inspect these fields.

>>> metrics.attributes
{'store.get.object_size': 219, 'store.put.object_size': 219}
>>> metrics.counters
{'store.get.cache_misses': 1}
>>> metrics.times
{
    'store.put.serialize': TimeStats(
        count=1, avg_time_ms=9.9, min_time_ms=9.9, max_time_ms=9.9
    ),
    'store.put.connector': TimeStats(
       count=1, avg_time_ms=36.9, min_time_ms=36.9, max_time_ms=36.9
    ),
    'store.put': TimeStats(
       count=1, avg_time_ms=53.4, min_time_ms=53.4, max_time_ms=53.4
    ),
    'store.get.connector': TimeStats(
       count=1, avg_time_ms=16.1, min_time_ms=16.1, max_time_ms=16.1
    ),
    'store.get.deserialize': TimeStats(
       count=1, avg_time_ms=7.6, min_time_ms=7.6, max_time_ms=7.6
    ),
   'store.get': TimeStats(
       count=1, avg_time_ms=45.6, min_time_ms=45.6, max_time_ms=45.6
   ),
}

Operations or events are represented by a hierarchical namespace. E.g., store.get.object_size is the serialized object size from the call to Store.get(). In metrics.attributes, we see the serialized object was 219 bytes. In metrics.counters, we see we had one cache miss when getting the object. In metrics.times, we see statistics about the duration of each operation. For example, store.get is the overall time Store.get() took, store.get.connector is the time spent calling Connector.get(), and store.get.deserialize is the time spent deserializing the object returned by Connector.get().

If we get the object again, we'll see the metrics change.

>>> store.get(key)
>>> metrics = store.metrics.get_metrics(key)
>>> metrics.counters
{'store.get.cache_hits': 1, 'store.get.cache_misses': 1}
>>> metrics.times['store.get']
TimeStats(count=2, avg_time_ms=24.4, min_time_ms=3.2, max_time_ms=45.6)

Here, we see that the second get resulted in a cache hit, and our average time for store.get dropped significantly.

Attributes of a TimeStats instance can be directly accessed.

>>> metrics.times['store.get'].avg_time_ms
24.4

Metrics with Proxies¶

Metrics are also tracked on proxy operations.

>>> proxy = store.proxy(target)

# Access the proxy to force it to resolve.
>>> assert target_proxy[0] == 0

>>> metrics = store.metrics.get_metrics(proxy)
>>> metrics.times
{
    'factory.call': TimeStats(...)
    'factory.resolve': TimeStats(...),
    'store.get': TimeStats(...),
    'store.get.connector': TimeStats(...),
    'store.get.deserialize': TimeStats(...),
    'store.proxy': TimeStats(...),
    'store.put': TimeStats(...),
    'store.put.connector': TimeStats(...),
    'store.put.serialize': TimeStats(...),
}

Calling Store.proxy() internally called Store.put(). Accessing the proxy internally resolved the factory so we also see metrics about the factory and store.get.

Warning

For metrics to appropriately be tracked when a proxy is resolved, the Store needs to be registered globally with register_store(). Otherwise, the factory will initialize a second Store to register and record its metrics to the second instance.

Metrics for Batch Operations¶

For batch Store operations, metrics are recorded for the entire batch. I.e., the batch of keys is treated as a single super key.

>>> keys = store.put_batch(['value1', 'value2', 'value3'])
>>> metrics = store.metrics.get_metrics(keys)
>>> metrics.times
{
    'store.put_batch.serialize': TimeStats(...),
    'store.put_batch.connector': TimeStats(...),
    'store.put_batch': TimeStats(...)
}

Aggregating Metrics¶

Rather than accessing metrics associated with a specific key (or batched key), time statistics can be aggregated over all keys.

>>> store.metrics.aggregate_times()
{
    'factory.call': TimeStats(...),
    'factory.resolve': TimeStats(...),
    'store.get': TimeStats(...),
    'store.get.connector': TimeStats(...),
    'store.get.deserialize': TimeStats(...),
    'store.proxy': TimeStats(...),
    'store.put': TimeStats(...),
    'store.put.connector': TimeStats(...),
    'store.put.serialize': TimeStats(...),
    'store.put_batch': TimeStats(...),
    'store.put_batch.connector': TimeStats(...),
    'store.put_batch.serialize': TimeStats(...),
}

Each of these TimeStats represents the aggregate over all keys.

The Python code used to generate the above examples can be found at github.com/proxystore/proxystore/examples/store_metrics.py.