timestamps = spark.createDataFrame(
    [
        [1, 1573820575],
        [2, 1573820580],
        [3, 1573820600],
        [4, 1573820603],
        [5, 1573820703],
        [6, 1573820713],
    ],
    ["id", "timestamp"]
)
previous_window = Window.partitionBy().orderBy("id")
timestamps = (
    timestamps.withColumn("previous_timestamp", lag(col("timestamp")).over(previous_window))
    .withColumn("time_diff", col("timestamp") - col("previous_timestamp"))
    .fillna({"time_diff": 0})
    .withColumn("is_new_session", when(col("time_diff") > 60, lit(1)).otherwise(lit(0)))
    .withColumn("session_number", lag(col("is_new_session"), default=0).over(previous_window) + col("is_new_session"))
    .withColumn("session_time_diff", when(col("is_new_session") == 1, lit(0)).otherwise(col("time_diff")))
)
timestamps.show()
timestamps.groupBy(["session_number"]).agg(
    first("id").alias("start_id"),
    spark_sum("session_time_diff").alias("duration")
).show()

+---+----------+------------------+---------+--------------+--------------+-----------------+
| id| timestamp|previous_timestamp|time_diff|is_new_session|session_number|session_time_diff|
+---+----------+------------------+---------+--------------+--------------+-----------------+
|  1|1573820575|              null|        0|             0|             0|                0|
|  2|1573820580|        1573820575|        5|             0|             0|                5|
|  3|1573820600|        1573820580|       20|             0|             0|               20|
|  4|1573820603|        1573820600|        3|             0|             0|                3|
|  5|1573820703|        1573820603|      100|             1|             1|                0|
|  6|1573820713|        1573820703|       10|             0|             1|               10|
+---+----------+------------------+---------+--------------+--------------+-----------------+

+--------------+--------+--------+
|session_number|start_id|duration|
+--------------+--------+--------+
|             0|       1|      28|
|             1|       5|      10|
+--------------+--------+--------+

No Partition Defined for Window operation! Moving all data to a single partition, this can cause serious performance degradation.