Redis · Ops · Hiring: remote redis-ops engineer (full-time, long-term)

294
REr/redis-ops·posted by alice_dev·3 days agoAnnouncement

Hiring: remote redis-ops engineer (full-time, long-term)

Some background first. Our setup is redis-ops plus three downstream services, seven figures of daily requests, peaking around nine in the evening.

One last trap: in container environments remember to adjust the memory-related parameters in step. Otherwise the host limit and the process expectation disagree, and the symptom is intermittent, unreproducible failure.

// Minimal reproduction: you must use a real long-tail distribution here.
// Uniform load-test traffic will never trigger this.
func (s *Server) handle(ctx context.Context) error {
    conn, err := s.pool.Acquire(ctx)
    if err != nil {
        return fmt.Errorf("acquire: %w", err)
    }
    defer conn.Release()

    return s.do(ctx, conn)
}

The first thing was to collapse the variables. We were changing config and upgrading the version at the same time, and afterwards nobody could say which change caused what. We rolled back to moving one variable at a time, re-ran three times, and only then did the curve settle. Tedious, but not skippable.

On trade-offs, my view is this: if nobody on the team owns this area long-term, do not introduce a second mechanism. With two coexistence you first have to work out which one is even in play when things break, and that costs far more than the performance you saved.

30 comments

30 comments

M
Kkite·yesterday

We have run this in production for two years without hitting it. That said, we never reached this scale, so our experience is not really evidence here.

418
Ttang_hao·2 days agoedited

Saved. I am reworking this area this week — this saves a lot of wrong turns.

3
Hhuang_ke·2 days ago

This is not a redis-ops problem, it is a usage problem. The docs say this API is not thread-safe and you must lock around it yourself.

255
Rran_bo·2 days ago

I see point 3 differently. The trade-off depends on your read/write ratio: read-heavy with little writing means caching actually widens the inconsistency window.

252
Hhuang_keOP·1 hour ago

Agreeing with the above. One addition: with this option enabled the GC count in your metrics doubles, so adjust the alert threshold at the same time or it will keep firing.

163
Sslow_query·2 days ago

Agreeing with the above. One addition: with this option enabled the GC count in your metrics doubles, so adjust the alert threshold at the same time or it will keep firing.

216
Mmike_xu·1 hour ago

There is actually a simpler fix that needs no architecture change: move this check up to the gateway and the problem disappears. The cost is one extra lookup at the gateway.

209
Cchen_dev·2 days ago

Has anyone run a controlled experiment? I did, reducing it to a single variable, and the difference was 4% — within noise. So I suspect the main cause is something else.

170
Llinlin·yesterdayedited

Has anyone run a controlled experiment? I did, reducing it to a single variable, and the difference was 4% — within noise. So I suspect the main cause is something else.

1
Bbob_chen·2 days ago

I see point 3 differently. The trade-off depends on your read/write ratio: read-heavy with little writing means caching actually widens the inconsistency window.

129
Wwinter·3 minutes ago

Worth learning from this debugging approach. We went straight at the logs and took a much longer route.

77
Rran_bo·2 hours ago

Saved. I am reworking this area this week — this saves a lot of wrong turns.

11
Rran_bo·3 minutes ago

I just read the redis-ops source — the author actually explains the reasoning in a comment, roughly "so that it degrades into predictable behaviour in extreme cases".

2
Sswoole_lee·yesterday

Can you give a minimal reproduction? I ran it locally for ten minutes and could not reproduce on macOS with the latest version.

168
Sswoole_lee·1 hour ago

Sharing our numbers, 8 cores 16GB, same scenario:

| Concurrency | P50 | P99 |
|---|---|---|
| 200 | 12ms | 88ms |
| 500 | 31ms | 340ms |

P99 clearly collapses at 500 concurrency, which lines up with your knee point.

1
Zzhou_yi·just now

We have run this in production for two years without hitting it. That said, we never reached this scale, so our experience is not really evidence here.

76
Bbob_chen·2 hours ago

This matches what we see in production. We only hit it past 3k QPS; the earlier load tests showed nothing — the test traffic was too clean, with no long-tail requests.

437
Rrase·3 minutes agoedited

Thanks for sharing real numbers — far more useful than the articles that only cover concepts.

42
Ddev_zhou·1 hour agoedited

Thanks for sharing real numbers — far more useful than the articles that only cover concepts.

1
Bbob_chen·12 minutes agoedited

Worth learning from this debugging approach. We went straight at the logs and took a much longer route.

321
Kkernel_panic·3 minutes ago

This matches what we see in production. We only hit it past 3k QPS; the earlier load tests showed nothing — the test traffic was too clean, with no long-tail requests.

7
Hhuang_ke·1 hour ago

A question: what changes in a container with a 512Mi memory limit? That is how we run it in production.

58
Kkite·just nowedited

Can you give a minimal reproduction? I ran it locally for ten minutes and could not reproduce on macOS with the latest version.

56
Llinlin·28 minutes ago

One counter-example: below redis-ops 7.4 the semantics of that code are different, so do not copy it verbatim. We got burned in staging and rolled back once.

279
Kkite·just now

Can you give a minimal reproduction? I ran it locally for ten minutes and could not reproduce on macOS with the latest version.

128
Sslow_queryMod·5 hours ago

This is not a redis-ops problem, it is a usage problem. The docs say this API is not thread-safe and you must lock around it yourself.

34
Zzhu_zong·2 days ago

One counter-example: below redis-ops 7.4 the semantics of that code are different, so do not copy it verbatim. We got burned in staging and rolled back once.

262
Kkite·1 hour ago

A question: what changes in a container with a 512Mi memory limit? That is how we run it in production.

114
Oops_wang·2 days ago

I just read the redis-ops source — the author actually explains the reasoning in a comment, roughly "so that it degrades into predictable behaviour in extreme cases".

7
Cchen_dev·2 days ago

Sharing our numbers, 8 cores 16GB, same scenario:

| Concurrency | P50 | P99 |
|---|---|---|
| 200 | 12ms | 88ms |
| 500 | 31ms | 340ms |

P99 clearly collapses at 500 concurrency, which lines up with your knee point.

226

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