CPU performance is degraded on version 0.22.1

Hello
I spent days searching for CPU issue in my Dynatrace Python extension (which is basicaly a prometheus scraper for a Solace prometheus exporter).

I finally noticed a big performance gap between versions 0.21.1 and 0.22.1.

0.22.1 consumes 4 times more CPU than 0.21.1. I finally downgraded to 0.21.1 and my CPU is back to normal state.

Here is my usage:

            # Prometheus parser: https://prometheus.github.io/client_python/parser/
            for prometheus_line in utf8_lines:
                for family in text_string_to_metric_families(prometheus_line):
                    for sample in family.samples:
                        skip = False # By default, no metric is skipped unless we filter it

                        if sample.name in wanted_solace_metrics:
                            found_metrics += 1
                            # self.logger.info("line: " + prometheus_line)
                            # print("Name: {0} Labels: {1} Value: {2}".format(*sample))

                            # NaN detection with math library
                            if math.isnan(sample.value):
                                invalid_metrics += 1
                                self.logger.info("NaN value skipped " + sample.name)
                                # If the value is NaN, we ignore it
                                break
                            else:
                                valid_metrics += 1
                                dims= {**sample[1], "node": nodename, "clustername": clustername}

                                # Remove unwanted dimensions
                                    #define the keys to remove
                                keys = ['client_name', 'client_address', 'client_profile', 'flow_id', 'acl_profile']
                                for key in keys:
                                    result_pop=dims.pop(key, None)
                                    if sample.name not in censored_metrics_list and result_pop is not None:
                                        # print("DETECTED")
                                        censored_metrics_list.append(sample.name)

                                # parse exporter errors
                                if "error" in dims.keys():
                                    solace_prometheus_exporter_error=str(dims["error"]).replace('\"',"").strip()
                                    sanitized_solace_prometheus_exporter_error={ "error": solace_prometheus_exporter_error}
                                    dims.update(sanitized_solace_prometheus_exporter_error)

                                # Remove unwanted queue protocols or modify queue names patterns
                                if "queue_name" in dims.keys():
                                    # avoid the ingestion issue with bad queue names with trailing \n
                                    queue_name=str(dims["queue_name"]).strip()
                                    sanitized_queue_name = { "queue_name": queue_name }

                                    # update the queue_name in the dims payload
                                    dims.update(sanitized_queue_name)

                                    queue_name_lower=queue_name.lower()
                                    if queue_name_lower.startswith('#mqtt') or queue_name_lower.startswith('#cfgsync') or queue_name_lower.startswith('#p2p') or queue_name_lower.startswith('#pq') or queue_name_lower == "":
                                    # if queue_name_lower.startswith('#cfgsync') or queue_name_lower.startswith('#p2p') or queue_name_lower.startswith('#pq') or queue_name_lower == "":

                                        skip = True

                                # Manage non skipped metrics
                                if skip is False:
                                    # Keeps queue quota calcuted metrics
                                    if sample.name == "solace_queue_spool_usage_bytes":
                                        queue_usage.append({ "metric_name": sample.name, "md5_dims": hashlib.md5(str(dims).encode("utf-8")).hexdigest(), **dims, "METRICvalueMETRIC": sample.value})
                                    if sample.name == "solace_queue_spool_quota_bytes": # we store this metrics in a separate table to calculate disk usage later
                                        queue_quota.append({ "metric_name": sample.name, "md5_dims": hashlib.md5(str(dims).encode("utf-8")).hexdigest(), **dims, "METRICvalueMETRIC": sample.value})

                                    # send valid points (with dimensions strings as md5 if necessary)
                                    if sample.name not in censored_metrics_list:
                                        # Append valid points
                                        valid_points.append( { "metric_name": sample.name, **dims, "METRICvalueMETRIC": sample.value})
                                    else:
                                        # if the metric is aggregated we add a md5sum of "all the dimensions" as an index to find duplicates and ease "groupby" without pandas
                                        valid_points.append( { "metric_name": sample.name, "md5_dims": hashlib.md5(str(dims).encode("utf-8")).hexdigest(), **dims, "METRICvalueMETRIC": sample.value})

If this code is still correct in 0.22.1, I think there is an issue in newer versions 0.22.x.

Best regards,
Charles

Start by comparing the 0.21.1 and 0.22.1 implementations around text_string_to_metric_families, using the reported Prometheus parsing loop as the reproduction workload. Measure CPU usage for both versions, identify the regression, and add a focused regression test or benchmark showing that the newer version no longer has the reported degradation.