How can you optimize indexing throughput in Solr?

Indexing throughput is usually limited by commit overhead, request overhead, or the ram buffer settings rather than raw CPU, so tuning those first tends to pay off the most.

1. Batch documents - send hundreds or thousands of documents per update request instead of one HTTP call per document; this amortizes network and parsing overhead.
2. Avoid committing per document - let autoCommit and autoSoftCommit intervals handle visibility instead of calling commit after every add.
3. Increase the RAM buffer size (ramBufferSizeMB) so more documents accumulate in memory before a segment flush, reducing the number of small segments created.
4. Use multiple indexing threads/clients in parallel, especially in SolrCloud where different shards can absorb writes concurrently.
5. Disable unnecessary update processors temporarily during bulk loads if they're not needed for that batch.

In SolrCloud specifically, indexing performance also depends on replica type: routing bulk loads at TLOG or NRT leaders directly, with PULL replicas absorbing read traffic, keeps indexing and query workloads from competing for the same resources.