src/vs/platform/storage/electron-main/storageMain.ts/BaseStorageMain/close
class BaseStorageMain:	async close(): Promise<void> {

		// Measure how long it takes to close storage
		const watch = new StopWatch(false);
		await this.doClose();
		watch.stop();

		// If close() is taking a long time, there is
		// a chance that the underlying DB is large
		// either on disk or in general. In that case
		// log some additional info to further diagnose
		if (watch.elapsed() > BaseStorageMain.LOG_SLOW_CLOSE_THRESHOLD && this.path) {
			try {
				const largestEntries = top(Array.from(this._storage.items.entries())
					.map(([key, value]) => ({ key, length: value.length })), (entryA, entryB) => entryB.length - entryA.length, 5)
					.map(entry => `${entry.key}:${entry.length}`).join(', ');
				const dbSize = (await this.fileService.stat(URI.file(this.path))).size;

				this.logService.warn(`[storage main] detected slow close() operation: Time: ${watch.elapsed()}ms, DB size: ${dbSize}b, Large Keys: ${largestEntries}`);

				type StorageSlowCloseClassification = {
					duration: { classification: 'SystemMetaData'; purpose: 'PerformanceAndHealth'; isMeasurement: true; comment: 'The time it took to close the DB in ms.' };
					size: { classification: 'SystemMetaData'; purpose: 'PerformanceAndHealth'; isMeasurement: true; comment: 'The size of the DB in bytes.' };
					largestEntries: { classification: 'SystemMetaData'; purpose: 'PerformanceAndHealth'; isMeasurement: true; comment: 'The 5 largest keys in the DB.' };
					owner: 'bpasero';
					comment: 'Used to gain insight into reasons a database may be slow. This is used to assist with further optimizations';
				};

				type StorageSlowCloseEvent = {
					duration: number;
					size: number;
					largestEntries: string;
				};

				this.telemetryService.publicLog2<StorageSlowCloseEvent, StorageSlowCloseClassification>('storageSlowClose', {
					duration: watch.elapsed(),
					size: dbSize,
					largestEntries
				});
			} catch (error) {
				this.logService.error('[storage main] figuring out stats for slow DB on close() resulted in an error', error);
			}
		}

		// Signal as event
		this._onDidCloseStorage.fire();
	}