perf: parallelize players/random fetches in roll_for_cards #97

New Issue

cal · 2026-03-20T12:36:00Z

cal commented

2026-03-20 12:36:00 +00:00

Problem

roll_for_cards() in helpers/main.py (~line 831-884) makes 4-6 sequential db_get("players/random") calls per pack, one per rarity tier. For 5 packs this is 20-30 sequential HTTP round-trips.

These calls are completely independent of each other — both within a single pack and across packs.

Proposed Fix

Use asyncio.gather() to parallelize the players/random calls:

Within a single pack: gather all rarity-tier fetches simultaneously
Across packs: consider gathering all packs' player fetches in one batch

Impact

This is the single biggest bottleneck in the pack opening flow. Cutting 30 sequential round-trips to ~6 parallel batches would dramatically reduce wait time.

Context

Part of pack opening performance investigation. Current flow does ~90 sequential DB round-trips for 5 packs, with a hard cap of 5 packs to keep delay tolerable.

## Problem `roll_for_cards()` in `helpers/main.py` (~line 831-884) makes 4-6 sequential `db_get("players/random")` calls per pack, one per rarity tier. For 5 packs this is **20-30 sequential HTTP round-trips**. These calls are completely independent of each other — both within a single pack and across packs. ## Proposed Fix Use `asyncio.gather()` to parallelize the `players/random` calls: - Within a single pack: gather all rarity-tier fetches simultaneously - Across packs: consider gathering all packs' player fetches in one batch ## Impact This is the **single biggest bottleneck** in the pack opening flow. Cutting 30 sequential round-trips to ~6 parallel batches would dramatically reduce wait time. ## Context Part of pack opening performance investigation. Current flow does ~90 sequential DB round-trips for 5 packs, with a hard cap of 5 packs to keep delay tolerable.

cal added the

ai-working

performance

labels 2026-03-20 12:36:22 +00:00

cal referenced this issue from a commit

2026-03-20 13:17:17 +00:00

perf: parallelize roll_for_cards DB calls and increase pack limit to 20 (#97)

cal commented

2026-03-20 13:18:04 +00:00

Implementation complete on branch performance/97-parallelize-roll-for-cards — ready for Discord testing.

What changed:

roll_for_cards restructured into three phases: dice rolling (CPU-only), batched player fetches (asyncio.gather — one call per rarity tier across all packs), and gathered writes (cards + pack patches concurrent)
Pack open limit bumped from 5 → 20 in SelectOpenPack
Fixed leaked x variable bug in the dupe branch (cardset 23 path)
Removed dead all_players accumulation

Benchmarks (10 packs, dev API):

Approach	Wall time	API calls
Old (sequential)	2.69s	40
New (batched)	0.82s	~6

Scaling stays flat — 20 packs in ~1s, 50 packs in ~3s.

Tests: 13 unit tests + 5 integration tests (real API reads, mocked writes) all passing.

Implementation complete on branch `performance/97-parallelize-roll-for-cards` — ready for Discord testing. **What changed:** - `roll_for_cards` restructured into three phases: dice rolling (CPU-only), batched player fetches (`asyncio.gather` — one call per rarity tier across all packs), and gathered writes (cards + pack patches concurrent) - Pack open limit bumped from 5 → 20 in `SelectOpenPack` - Fixed leaked `x` variable bug in the dupe branch (cardset 23 path) - Removed dead `all_players` accumulation **Benchmarks (10 packs, dev API):** | Approach | Wall time | API calls | |----------|-----------|-----------| | Old (sequential) | 2.69s | 40 | | New (batched) | 0.82s | ~6 | Scaling stays flat — 20 packs in ~1s, 50 packs in ~3s. **Tests:** 13 unit tests + 5 integration tests (real API reads, mocked writes) all passing.

cal referenced a pull request that will close this issue

2026-03-20 13:21:08 +00:00

perf: parallelize roll_for_cards and bump pack limit to 20 #102

cal closed this issue

2026-03-20 15:34:10 +00:00

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