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# Isolated Execution
Sometimes you want to run your commands on an exclusive connection. There are a few reasons to do this:
- You're using [transactions]() and need to `WATCH` a key or keys for changes.
- You want to run a blocking command that will take over the connection, such as `BLPOP` or `BLMOVE`.
- You're using the `MONITOR` command which also takes over a connection.
Below are several examples of how to use isolated execution.
> NOTE: Behind the scenes we're using [`generic-pool`](https://www.npmjs.com/package/generic-pool) to provide a pool of connections that can be isolated. Go there to learn more.
## The Simple Scenario
This just isolates execution on a single connection. Do what you want with that connection:
```typescript
await client.executeIsolated(async isolatedClient => {
await isolatedClient.set('key', 'value');
await isolatedClient.get('key');
});
```
## Transactions
Things get a little more complex with transactions. Here we are `.watch()`ing some keys. If the keys change during the transaction, a `WatchError` is thrown when `.exec()` is called:
```typescript
try {
await client.executeIsolated(async isolatedClient => {
await isolatedClient.watch('key');
const multi = isolatedClient.multi()
.ping()
.get('key');
if (Math.random() > 0.5) {
await isolatedClient.watch('another-key');
multi.set('another-key', await isolatedClient.get('another-key') / 2);
}
return multi.exec();
});
} catch (err) {
if (err instanceof WatchError) {
// the transaction aborted
}
}
```
## Blocking Commands
For blocking commands, you can execute a tidy little one-liner:
```typescript
await client.executeIsolated(isolatedClient => isolatedClient.blPop('key'));
```
Or, you can just run the command directly, and provide the `isolated` option:
```typescript
await client.blPop(
commandOptions({ isolated: true }),
'key'
);
```
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