Payment Timeout

Use kprobe when a payment fails or slows down and the normal tools only show a timeout.

Symptom

payment pay_123 failed
ledger-service timeout after 750ms

Logs show the timeout. Traces show the ledger service was slow. Neither explains why the ledger service was slow.

What kprobe captures

kprobe records:

• ingress request timing
• service process activity
• read and write syscall latency
• disk I/O stalls
• TCP retransmits
• scheduler delay
• memory pressure events

Investigation

Search for:

payment_id = pay_123

Open the causal graph:

ledger timeout
  <- database write syscall delayed
  <- block I/O queued behind compaction
  <- node-level storage saturation

Result

Instead of stopping at “ledger timed out,” kprobe shows the machine-level cause that pushed the payment past its timeout budget.