mate-symfony-profiler-debugging

name	mate-symfony-profiler-debugging
description	Diagnose a Symfony request that failed, errored (5xx), or was slow, using the profiler. Use when a specific request misbehaved and the app has the profiler enabled (usually dev). Not for cross-request trends over time (use log investigation) or DI wiring bugs (use service inspection).

Profiler debugging

Reads the profiler through Mate's CLI. Two tools, two resources:

• symfony-profiler-list filters profiles (method, url, ip, statusCode, context, from, to, limit). Newest first, so --limit=1 is the latest. Returns summaries with a resource_uri per profile.
• symfony-profiler-get --token=<t> returns one profile's metadata. It does NOT list collectors.
• symfony-profiler://profile/{token} lists the collectors this profile actually has, each with its URI.
• symfony-profiler://profile/{token}/{collector} returns that collector, as {name, data, summary}. summary is the triage view, data the full detail.

These commands accept --format: json to parse the result, toon (when helgesverre/toon is installed) for the smallest context footprint. On a large profile, prefer one of these over the human-readable default.

Workflow

1. Find the profile. Do not scroll all profiles.
   • Error: vendor/bin/mate tools:call symfony-profiler-list --statusCode=500 --limit=5
   • Known URL: --url=/checkout. Latest request: --limit=1.
2. vendor/bin/mate resources:read symfony-profiler://profile/<token> to see which collectors exist. Apps differ; only read what is present.
3. Read collectors in diagnosis order, not all of them.

Reading order

Branch on the symptom.

Errored (5xx / exception): read exception first. data.class, message (secrets scrubbed), file, line, and trace (top 10 frames) are the fix. If has_exception is false on an error response, the failure is upstream: check request for the status and logger for what was logged.

Slow but succeeded: skip exception, go to time, then db, then memory.

• time: duration_ms is total. events are sorted slowest first with a category (e.g. doctrine, template, controller) that tells you which subsystem ate the time. That category picks the next collector.
• db: query_count plus summary.duplicate_query_count. queries are grouped by identical SQL, sorted by total_time_ms. An N+1 shows as one grouped entry with a high count (same statement fired in a loop), or a high duplicate_query_count. One slow statement shows as a high avg_time_ms. sample_params shows what was bound. Grouped list caps at 50 (queries_truncated).
• memory: usage_percent against the limit. Only relevant when the request is heavy or OOMs.

Wrong output / bad input: read request. summary has method, path, route, status_code, content_type. data has the sanitized bags (request_query, request_request, request_headers, session_attributes). Sensitive values, the raw body, and the curl command are redacted or omitted by design, so do not expect to read a password back.

Tie a log line to the request: logger has error_count / warning_count / deprecation_count and the per-request logs (message, level, channel, context; capped at 100). Use it to see what the code logged during exactly this request, which the global log files cannot pin to one request.

Other collectors present in the profile (router, security, twig, ...) are readable at the same URI shape; they return raw dumps rather than a curated shape.

Failure paths

• symfony-profiler-list returns no profiles: the profiler is off (not enabled, or prod), or nothing has been requested since it was cleared. Fall back to log investigation.
• symfony-profiler-get on a stale/wrong token errors with "Profile ... not found". Re-list to get a live token; tokens change when the profiler storage is cleared.
• A collector URI returns {"error": ...} instead of data: that collector is not in this profile, or the name is wrong. Re-read symfony-profiler://profile/{token} for the real names.
• The failing request was a sub-request: the profile has a parent_token / parent_profile. The real exception often sits on the parent, not the fragment.