Photoshop 2026.3: Batch Processing Concurrency – File Locking Without Control

Direct answer

No. Photoshop 2026.3 does not provide a hidden or experimental flag to serialize access to the same source PSD during concurrent Automate > Batch runs, and the Photoshop API / scripting interface does not expose job queue ordering, prioritization, or inspection. There is no documented setting to enforce exclusive file access or guarantee FIFO execution for concurrent batch jobs.

Confirmed facts are separated from likely explanation below.

Confirmed facts from scripting and Automate

• File > Automate > Batch runs as a separate Photoshop process or script session per invocation. There is no built-in job queue shared between invocations.
• ExtendScript / UXP scripting DOM provides app.open() with an optional asCopy parameter. No exclusive-lock flag exists.
• No lock, queue or priority API is documented in the Photoshop Scripting Guide or UXP API reference as of the 2024/2025 release line. No preference in ~/Library/Preferences/Adobe Photoshop Settings or Windows registry controls serialization.
• UXP plugins run in a single-threaded event loop per Photoshop instance. They cannot coordinate across separate Photoshop processes without an external broker.

Likely explanation for the latency spikes

The observed serialization and non-deterministic order is not a Photoshop-managed queue. When multiple batch jobs launch concurrently and target the same large PSD, latency is most likely caused by OS-level file handle contention, scratch disk I/O, GPU/CPU memory pressure, and Photoshop opening the file independently in each process. Completion order is determined by the OS process scheduler, not by Photoshop.

Scoped steps for this case

1. Do not rely on Photoshop to serialize. Wrap each batch launch with an external mutex.
2. On macOS, serialize with a lock directory or flock around the launch command, e.g., osascript / photoshop -r script.jsx. On Windows, use a lock file / named mutex around photoshop.exe -r script.jsx.
3. If the source PSD is used only as a template, open it once per Photoshop instance and work on duplicates in memory: var src = app.open(file); var dup = src.duplicate(); then run actions on dup. This removes concurrent file I/O on the original PSD.
4. Use an external orchestrator to maintain a single job queue and invoke Photoshop sequentially via COM on Windows or osascript on macOS. Examples are custom Node/Python wrappers or CLI wrappers that queue jobs before launching Photoshop.

One diagnostic detail changes the recommendation: do your batch jobs modify the source PSD on disk, or do they only read it as a read-only template and write outputs elsewhere? Write-back requires strict exclusive locking; read-only template use can be solved by in-memory duplication.