Expensive Serialization in Loop¶

Rule details


Rule ID	`expensive-serialization-in-loop`
Severity	WARNING — likely performance problem
Confidence	MEDIUM — likely correct, some context-dependent
Category	Loop amplifiers
Complexity	O(n·serialize) → O(n)

Description¶

Detects serialization or deserialization calls inside loops. Operations like writeValueAsString(), readValue(), or JSON.stringify() are themselves O(n) over the object graph — calling them inside a loop compounds the cost.

Typical¶

JavaJavaScript

for (Order order : orders) {
    String json = objectMapper.writeValueAsString(order); // Serialization per iteration
    messages.add(json);
}

orders.forEach(order => {
    const json = JSON.stringify(order); // Serialization per iteration
    messages.push(json);
});

After¶

String json = objectMapper.writeValueAsString(orders); // Serialize the whole batch once
sendBatch(json);

When individual serialization is required, consider whether the loop itself is necessary — often the consumer can accept a batch.

Suggestion¶

Move serialization outside the loop, or use batch serialization