Shanghai software engineer Wu Linfeng watched the silent comedy "Modern Times" recently and soon found himself crying -- watching Charlie Chaplin's classic stressed-out assembly-line worker was like watching himself.

Overworked, underpaid, and feeling like a hamster on a wheel, he is among China's masses of mostly male tech-industry staff whose long hours have sparked a national debate about work-life balance.

The coders, engineers, programmers, software developers, game designers and other IT manpower behind China's burgeoning digital economy have become known as "996" workers due to the 9am-9pm, six-day week they work, without overtime pay.

Wu, who asked that a pseudonym be used to protect his job, has followed that schedule for three years at a leading Chinese internet company.

"You're the first girl I've spoken to in about a year," he told an AFP reporter, with just a hint of exaggeration.

Chinese tech companies have grown rapidly along with the country's digital transformation, becoming giants at home while some like Huawei and Alibaba are globally recognised brands.

The millions of tech workers behind their success had for years attracted little attention, but the issue went viral recently with the anonymous release online of a "blacklist" of Chinese companies where "996" prevails.

The list this week reached 139 companies, including fast-growing e-commerce platform Pinduoduo, messaging and games giant Tencent, and Bytedance, creator of popular apps and content platforms.

Its host page, located at 996.ICU -- because working those hours supposedly puts you in intensive care -- has been translated into more than 20 languages.

Work till you drop

As China marks the May Day worker's holiday on Wednesday, the affair has sparked national soul-searching over whether China's rapid modernisation was creating a work-till-you-drop culture.

The 996 hashtag on China's popular Weibo platform has been viewed more than 15 million times, with many comments criticising companies and the government for not enforcing laws limiting work hours.

"They say (China) is led by the working class," said one post, an apparent reference to the Communist Party.

"But have you ever seen leaders exploited like this?"

A video game designer who withheld his name told AFP he once spent 110 straight hours in the office, sleeping and eating there, to keep up with work.

After years of hard toil, the 31-year-old suffers endocrine disorders and depression, which he blames on excessive work.

"I don't get a sense of achievement, and I'm hardly getting rich," he said.

"My hourly wage is even lower than our office cleaning lady."

Working excessive hours is viewed as vital to surviving in the competitive industry, tech workers told AFP.

Employers will often stipulate "flexible" work schedules in job contracts while setting unrealistic performance goals requiring workers to burn the midnight oil.

Huge blessing?

Leading tech tycoons have stoked the debate.

Alibaba founder Jack Ma, called "996" a "huge blessing" for go-getters who strive for success, while Richard Liu, the head of Alibaba's e-commerce rival JD.com, denounced those unwilling to work hard as "slackers".

Their comments drew widespread criticism.

Chinese tech workers average around $5 per hour worked, according to leading Chinese recruitment app Boss Zhipin -- one-fifth of what their Japanese counterparts make, and one-tenth of Silicon Valley employees, according to various data sources.

"If you are unwilling to do the work, others are standing in line, waiting to replace you," said a software engineer -- a "code peasant", as he puts it -- who also declined to give his name.

Japan was long viewed as the standard-setter on overwork, but a new labour law there limits monthly overtime to 45 hours, while South Korea last year cut its maximum workweek to 52 hours, from 68.

Chinese authorities have yet to wade into the debate, but Communist Party mouthpiece the People's Daily said in a recent editorial that "996" violates laws stipulating a 40-hour workweek.

"An extended 996 schedule does great harm to employee morale, makes them extremely fatigued, may cause mental disorders and negatively influence their family lives," said Su Yong, dean of the Institute of Oriental Management in Shanghai's Fudan University.

"Companies should focus on cultivating smart, creative and more productive staff rather than increasing working hours."

Still, a nose-to-the-grindstone culture remains strong in China, and many web users said the gainfully employed should feel grateful.

"If you don't strive when you are young, do you truly want to regret your mediocrity when you are old?" said one.