fix: use an independent sql connection for mempool stats (#2217)

Author: rafaelcr

src/datastore/pg-write-store.ts

@@ -2034,8 +2034,13 @@ export class PgWriteStore extends PgStore {
     this._debounceMempoolStat.debounce = setTimeout(async () => {
       this._debounceMempoolStat.running = true;
       this._debounceMempoolStat.triggeredAt = null;
+      const sql = await connectPostgres({
+        usageName: `mempool-debounce`,
+        connectionArgs: getConnectionArgs(PgServer.primary),
+        connectionConfig: getConnectionConfig(PgServer.primary),
+      });
       try {
-        const mempoolStats = await this.sqlTransaction(async sql => {
+        const mempoolStats = await sql.begin(async sql => {
           return await this.getMempoolStatsInternal({ sql });
         });
         this.eventEmitter.emit('mempoolStatsUpdate', mempoolStats);
@@ -2052,6 +2057,7 @@ export class PgWriteStore extends PgStore {
           logger.error(e, `failed to run mempool stats update`);
         }
       } finally {
+        await sql.end();
         this._debounceMempoolStat.running = false;
         this._debounceMempoolStat.debounce = null;
         if (this._debounceMempoolStat.triggeredAt != null) {