Its leaders said it would end in 39 days and, indeed, when Feb. 21 arrived, the Virginia General Assembly adjourned after completing the shortest annual session in memory.

But brevity had its price, and many lawmakers say the 1981 session will be remembered largely not for what it did, but for what it failed to do.

"It's like trying to put 10 pounds of sugar in a 5-pound bag," said Alexandria Sen. Wiley F. Mitchell, who predicted early on that the session would prove too hectic for constructive work. By the session's end, an angry Fairfax Sen. Adelard Brault was promising to filibuster any effort to cram so much work into so little time again.

The major failure was in the area of tax relief. Three major tax-cut measures -- to cut in half the state's 4 percent sales tax on food, to repeal the tax on nonprescription drugs and to revamp the state's income tax structure -- passed the House of Delegates only to be scuttled by the powerful Senate Finance Committee and its patriarchal chairman, Richmond Sen. Edward E. Wiley.

The gruff, conservative Wiley proved to be this year's central figure in the tax fight, viewing himself as the only guardian against raids on the state treasury by election-crazed delegates. In the end, the only tax bill to survive Wiley's ax was a measure he cosponsored, which would advance to July the effective date of a bill to repeal the sales tax on home heating fuels. The repeal was scheduled for July 1982.

Wiley and his House counterpart, Appropriations Chairman Richard Bagely of Hampton, also shepherded Gov. John N. Dalton's program for spending the state's $201 budget surplus. Despite efforts from legislative mavericks, the money ended up almost exactly where Dalton wanted it to go -- to local education, the state prison system, the deficit-ridden Medicaid program and a 9 percent pay raise for state employes.

The tax-cut bills were but one indication that the delegates were sensitive -- some said "politically paranoid" -- about their prospects in this fall's election. For example, the Assembly overwhelmingly passed a constitutional amendment to limit state spending this session, a measure that was virtually laughed off the floor last year.

Delegates also approved a hurriedly drafted measure adding multiple murders to the list of crimes punishable by death, then had to go back and reamend the bill after learning it could have rendered the state's entire death penalty law unconstitutional. Last year, the bill died in committee.

The session was not devoid of achievements. After four years of wrangling between women's advocates and the defense lawyers who dominate the House Courts of Justice Committee, the Assembly approved major revisions in the state's sexual assault laws. And a bill that makes involuntary sterilizations virtually impossible to put an official end to a tragic era when patients hospitalized in mental institutions were forced to undergo sterilizations.

Special interests got some of what they wanted. For the steel and coal industries, there was a bill requiring the state to use domestic steel in public works projects. Restaurant owners lobbied heavily and won repeal of the $2-per-gallon state tax on the liquor they buy. Buyers of luxury boats will no longer pay the state's 4 percent sales tax, only a 2 percent titling tax.

But even entrenched interest groups lost a few. An attempt by banks and retail merchants to have the yearly interest ceiling on credit card purchases raised from the present 18 percent to 24 percent died in committee. "Any other year but election year, that would have passed," said Fairfax Sen. Richard L. Saslaw, who predicted the lobbyists would return again next year.

Here is a summary of other major action the Assembly took -- or refused to take:

A Brault-sponsored bill to tighten the legislative ethics laws died in a House committee, killed largely by the small, but influential group of lawyer-legislators who have been most often criticized for alleged conflicts of interest. Under the present law, lawyer-legislators can argue cases before the very state agencies whose budgets and personnel they control and can introduce bills to aid law clients with little fear of challenge.

The ethics question also was raised over a successful bill to aid negligence lawsuit plaintiffs. It was sponsored by Richmond De. George Allen, head of one of the state's largest negligence law firms. In an unusual public debate, Brault denounced Allen for "feathering his own nest" while Allen noted Brault's Fairfax law firm represented insurance companies that the bill might hurt. The bill passed but was vetoed by Dalton, himself a former insurance lawyer, who said he believed the measure would lead to higher insurance premiums for the state's motorists.

Virginia 18-year-olds may still drink beer in bars and restaurants, but a measure sponsored by Del. Warren Barry (R-Fairfax) will prohibit anyone under 19 from buying beer to take elsewhere. The law is an attempt to hold down drunk-driving deaths among teen-agers, especially in Northern Virginia. Passage of the bill was seen as a victory for restaurant owners who for four years blocked efforts to raise the drinking age to 21.

Many Northern Virginia homeowners would have found themselves paying increased state income taxes under a measure that would have eliminated itemized deductions and replaced them with a single standard deduction. The bill passed the House, but died in the Senate Finance Committee after area real estate dealers and other flooed lawmakers with angry calls and letters.

Proposals granting Medicaid payments for abortions in cases of rape, incest or gross fetal deformity were approved but may be vetoed by Dalton. Lt. Gov. Charles S. Robb, a Democrat and the Senate's presiding officer, broke a tie to pass one of the bills, a move that could become a controversial campaign issue when he seeks the governor's seat later this year.

The Equal Rights Amendment died without a hearing in a House committee, marking the eighth straight year Virginia has refused to ratify the measure.

The House Courts of Justice Committee, composed entirely of lawyers, killed a bill that would have weakened the committee's power to handpick judges by setting up a 15-member judicial advisory commission. The measure was opposed by groups like the NAACP on the grounds that such a commission would be unlikely to appoint blacks and women to judgeships.

The lawmakers ignored lobbying by organized labor groups and approved a bill that would life requirements for binding arbitration in Metro salary negotiations, but the measure faces an uncertain future in the District, Maryland and in Congress. All must approve the proposal, requested by the Metro board and by Northern Virginia localities as a way to hold down escalating transit costs.

Fairfax County won permission to build its own roads, provided the county obtains approval from local voters for expenditures expected to run between $5 and $10 million annually. Officials of the heavily congested county had complained the state's dwindling highway funds were inadequate to keep up with local road needs.

Northern Virginia also will be albe to require owners of multi-family dwellings to install smoke detectors. The measure faced opposition from construction and landlord interests who settled for a provision that makes tenants responsible for maintaining the detectors.

A compromise bill making it a felony to sell drug paraphernalia to minors was approved in the last hours of the session. An earlier version of the bill was torpedoed after lawmakers noted an identical measure had been found unconstitutional in several court tests.

The measure was supported by Northern Virginia legislators, who were fearful a similar law in Maryland might drive paraphernalia dealers from that state into their area.

The Assembly approved a bill restricting the use of strip searches in local jails. The bill was inspired by incidents in the Arlington County Jail where deputies until recently conducted strip searches of anyone jailed there, even those held for minor offenses.